Computer numerical controls (CNCs) are machines used to produce products in a factory setting. They have been in use for many years, and in the last decade, their use has become more widespread due to increased connectivity. This increased connectivity has made them more software-dependent and therefore more vulnerable to attacks. This vulnerability is due to the heterogeneity of technologies used in factories and the lack of awareness among users of how to best secure these systems.
This three-part blog series explores the risks associated with CNC machines. We performed a security evaluation on four representative vendors and analyzed technological developments that satisfy the Industry 4 .0 paradigm while conducting practical attacks against real-world installations.
For our research, we picked vendors that are:
Are geographically distributed (that is, with headquarters and subsidiaries spread across the world) and resell on a global scale.
Have been on the market for decades.
Have a large, estimated size, for example, with a total annual revenue of at least a billion US dollars.
Use technologies widely adopted in the domain and present in different manufacturing sectors.
Understanding numerical control machines
A machine tool is a device that uses cutting tools to remove material from a workpiece. This process, called machining, results in the desired geometry of the workpiece. Machining is a subtractive process, meaning that the material is removed from the original geometry to create the desired shape.
Numerical control (NC) is a technology that allows machines to be controlled by computers. This technology has revolutionized machine tools, making them more accurate and allowing for greater flexibility in their use. NC machine tools are now widely used in production systems and can be used on other types of machines, such as lasers and bending machines.
Basic concepts
To facilitate the understanding of what we discovered in our research, we introduce some basic concepts related to the use of machine tools:
Figure 1. Parts of a CNC machine
Numerical control. The NC is the most critical element of the machine, as it controls the entire process. This system includes visual programming functions to speed up the setup of production cycles. Additionally, the NC is always equipped with a human-machine interface (HMI) to facilitate operator interaction with control.
Programming. Initially developed in the 1950s, G-code (aka RS-274) is the predominant programming language in the world of machine tools. It is presented as a series of instructions initialized by a letter address, which follow one another on successive lines separated by paragraph breaks; each of these lines is called a “block.” Each letter address specifies the type of movement or function called by the user in that part of the program.
Parametric programming. Parametric programming is a way to make programs that are adjustable to different values. This is done by using variables that the user can input, and then the program will change based on those values. This is used in machine tools to help with things like feedback and closed-loop controls between production systems.
Single step. This allows for running the work program one line of code at a time. In this way, the operator can check the correspondence of executed code to the best possible working conditions and determine if intervention by modification is necessary.
Feed hold. The “feed hold” function is mainly used to check the correct execution of complex features by inspecting the work area before proceeding with further steps in the process. In fact, chips coming from the removal of the material being processed could be deposited in work areas or on measuring probes, potentially invalidating the measurements, or inducing defects downstream of the machining if they are not removed.
Tools. The machining process is a manufacturing technique that uses an element called a tool to remove excess material from a raw piece. The tool cutting is made possible by the relative speed between the manufacturing part and the cutting tool edge, also known as the cutting speed or surface speed. In addition to this parameter, the feed rate (speed of tool moving along workpiece) also affects chip removal process. Many types of tools are available depending on the type of processing needed.
Evaluating vendors
For all vendors that we included in our research scope, we conducted an equal evaluation of their machines:
The “Industry 4.0–ready” technologies are interfaces and related protocols used by machines in smart environments to transmit information outwards, towards centralized systems like production data for better management or cost reduction; they also enable remote management such that an operator can change the executed program without needing local access.
We identified potential vulnerabilities in the exposed services using automated scanners like Nessus. These included known or misconfigurations that could pose as dangerous, which we ignored to focus on domain-specific abuse cases for CNC interfaces instead.
We then went deep into the CNC-specific technologies previously identified, by analyzing the risks of abuses and conducting practical attacks on the controllers. For this, we developed attack tools that exploited the weaknesses we identified in the domain-specific interfaces with the aid of proprietary APIs we got access to.
We collected evidence of our concerns and collaborated with vendors to suggest mitigations. All evidence came from tests we conducted on real-world installations, but we also used simulators for preliminary testing or when the machines were not immediately available.
Now that we have established a better understanding of numerical control machines and their basic concepts, we will further explore the vendors we chose for this research in part two of the series. There, we’ll discuss how we evaluated vendors and what we discovered during our research.
When the headlines focus on breaches of large enterprises like the Optus breach, it’s easy for smaller businesses to think they’re not a target for hackers. Surely, they’re not worth the time or effort?
Unfortunately, when it comes to cyber security, size doesn’t matter.
Assuming you’re not a target leads to lax security practices in many SMBs who lack the knowledge or expertise to put simple security steps in place. Few small businesses prioritise cybersecurity, and hackers know it. According to Verizon, the number of smaller businesses being hit has climbed steadily in the last few years – 46% of cyber breaches in 2021 impacted businesses with fewer than 1,000 employees.
Securing any business doesn’t need to be complex or come with a hefty price tag. Here are seven simple tips to help the smaller business secure their systems, people and data.
Every organisation has anti-virus on their systems and devices, right? Unfortunately, business systems such as web servers get overlooked all too often. It’s important for SMBs to consider all entry points into their network and have anti-virus deployed on every server, as well as on employees’ personal devices.
Hackers will find weak entry points to install malware, and anti-virus software can serve as a good last-resort backstop, but it’s not a silver bullet. Through continuous monitoring and penetration testing you can identify weaknesses and vulnerabilities before hackers do, because it’s easier to stop a burglar at the front door than once they’re in your home.
Your perimeter is exposed to remote attacks because it’s available 24/7. Hackers constantly scan the internet looking for weaknesses, so you should scan your own perimeter too. The longer a vulnerability goes unfixed, the more likely an attack is to occur. With tools like Autosploit and Shodan readily available, it’s easier than ever for attackers to discover internet facing weaknesses and exploit them.
Even organisations that cannot afford a full-time, in-house security specialist can use online services like Intruder to run vulnerability scans to uncover weaknesses.
Intruder is a powerful vulnerability scanner that provides a continuous security review of your systems. With over 11,000 security checks, Intruder makes enterprise-grade scanning easy and accessible to SMBs.
Intruder will promptly identify high-impact flaws, changes in the attack surface, and rapidly scan your infrastructure for emerging threats.
Your attack surface is made up of all the systems and services exposed to the internet. The larger the attack surface, the bigger the risk. This means exposed services like Microsoft Exchange for email, or content management systems like WordPress can be vulnerable to brute-forcing or credential-stuffing, and new vulnerabilities are discovered almost daily in such software systems. By removing public access to sensitive systems and interfaces which don’t need to be accessible to the public, and ensuring 2FA is enabled where they do, you can limit your exposure and greatly reduce risk.
A simple first step in reducing your attack surface is by using a secure virtual private network (VPN). By using a VPN, you can avoid exposing sensitive systems directly to the internet whilst maintaining their availability to employees working remotely. When it comes to risk, prevention is better than cure – don’t expose anything to the internet unless it’s absolutely necessary!
New vulnerabilities are discovered daily in all kinds of software, from web browsers to business applications. Just one unpatched weakness could lead to full compromise of a system and a breach of customer data; as TalkTalk discovered when 150,000 of its private data records were stolen.
According to a Cyber Security Breaches Survey, businesses that hold electronic personal data of their customers are more likely than average to have had breaches. Patch management is an essential component of good cyber hygiene, and there are tools and services to help you check your software for any missing security patches.
Ransomware is on the increase. In 2021, 37% of businesses and organisations were hit by ransomware according to research by Sophos. Ransomware encrypts any data it can access, rendering it unusable, and can’t be reversed without a key to decrypt the data.
Data loss is a key risk to any business either through malicious intent or a technical mishap such as hard disk failure, so backing up data is always recommended. If you back up your data, you can counter attackers by recovering your data without needing to pay the ransom, as systems affected by ransomware can be wiped and restored from an unaffected backup without the attacker’s key.
Cyber attackers often rely on human error, so it’s vital that staff are trained in cyber hygiene so they recognise risks and respond appropriately. The Cyber Security Breaches Survey 2022 revealed that the most common types of breaches were staff receiving fraudulent emails or phishing attacks (73%), followed by people impersonating the organisation in emails or online (27%), viruses, spyware and malware (12%), and ransomware (4%).
Increasing awareness of the benefits of using complex passwords and training staff to spot common attacks such as phishing emails and malicious links, will ensure your people are a strength rather than a vulnerability.
Cyber security measures should always be appropriate to the organisation. For example, a small business which handles banking transactions or has access to sensitive information such as healthcare data should employ far more stringent security processes and practices than a pet shop.
That’s not to say a pet shop doesn’t have a duty to protect customer data, but it’s less likely to be a target. Hackers are motivated by money, so the bigger the prize the more time and effort will be invested to achieve their gains. By identifying your threats and vulnerabilities with a tool like Intruder, you can take appropriate steps to mitigate and prioritize which risks need to be addressed and in which order.
Attacks on large companies dominate the news, which feeds the perception that SMBs are safe, when the opposite is true. Attacks are increasingly automated, so SMBs are just as vulnerable targets as larger enterprises, more so if they don’t have adequate security processes in place. And hackers will always follow the path of least resistance. Fortunately, that’s the part Intruder made easy…
Intruder is a cyber security company that helps organisations reduce their attack surface by providing continuous vulnerability scanning and penetration testing services. Intruder’s powerful scanner is designed to promptly identify high-impact flaws, changes in the attack surface, and rapidly scan the infrastructure for emerging threats. Running thousands of checks, which include identifying misconfigurations, missing patches, and web layer issues, Intruder makes enterprise-grade vulnerability scanning easy and accessible to everyone. Intruder’s high-quality reports are perfect to pass on to prospective customers or comply with security regulations, such as ISO 27001 and SOC 2.
Intruder offers a 14-day free trial of its vulnerability assessment platform. Visit their website today to take it for a spin!
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[German]As of October 17, 2022, Microsoft has released several unscheduled updates for Windows. These updates fix a connection problem that can occur with SSL and TLS connections. Affected by this problem are probably all Windows client and server. Below I have listed all available updates and also give some hints where problems occur without these updates.
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Out-of-band updates with TLS fix
Microsoft made a mistake with the last updates for Windows (preview updates from September, security updates from October). As a result, various problems with SSL and TLS connections can occur. Microsoft has therefore released some : out-of-band updates on October 17, 2022 to fix the problem.
The out-of-band updates KB5020439 and KB5020440 were added on October 18th. These updates are only available for download in the Microsoft Update Catalog and have to be installed manually (just search for the KB numbers). Details about these updates can be found in the linked KB articles.
So only Windows 11 22H2 is missing the corresponding fix update. EP writes here that this fix will be added with the upcoming update KB5018496. This is currently released in the Windows Insider program as a pre-release version in the Release Preview channel (see).
Problems fixed with the updates
People have asked in comments which applications are actually affected by the TLS bugs. I don’t have a complete list, but would like to give some hints below as to what has come to my attention as a fix. Thanks to blog readers for the pointers.
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Citrix connectivity issue
With the October 2022 updates, administrators found that Citrix clients could no longer communicate with Citrix netscalers. I had reported on this in the blog postCitrix connections broken after Windows update KB5018410 (October 2022) (TLS problem). Affected people who installed the above updates reported that this fixed the connection problem.
KB5020387 fixes TLS 1.3 problem on Windows 10
On Windows, there was also the issue that there TLS 1.3 implementation was buggy on Windows 10 (it only works in Windows 11). I had raised a conflict case in the blog post Bug: Outlook no longer connects to the mail server (October 2022). Microsoft suggested disabling TLS 1.3 via registry intervention as a workaround. In this comment, someone suggests uninstalling updates KB5018410 (Windows 10) and KB5018427 (Windows 11).
Blog reader Harvester asked here, whether TLS 1.3 works with Windows 10 after installing the special updates, and then followed up with the results of his own tests.
Self-reply after tests : Schannel is working properly after having applied KB5020387 on a LTSC 2021 IoT Enterprise image (21H2), where Schannel was previously broken (on build 19044.2130, from October 11 2022)
We initially guessed that the IoT Enterprise SKU wasn’t supporting TLS 1.3, but now we confirmed that we hit the bug mentioned in the post.
“Fun” fact : while it as initially reported that TLS 1.3 was available starting from Windows 10 1903, the Schannel documentation was changed recently, and now state that only Windows 11 and Server 2022 support TLS 1.3: Protocols in TLS/SSL (Schannel SSP)
VPN and WebEx Meetings App
Within this German comment blog reader Marten reported, that the WebEx Meetings App could no longer connect to the WebEx Server (OnPrem) via VPN. The issue has been fixed via update.
Quest Migration Manager for Exchange
On Twitter, enno0815de has sent the following tweet, which refers to my message about the out-of-band updates with TLS fix. It says, anyone planning a domain migration using Quest Migration Manager for Exchange should also install the updates. Otherwise, the account will be locked out for the migration.
In a follow up tweet he adds: By some circumstance the Atelia class (Quest component) is deleted from the registry. Without the TLS fix, you lock the user out of AD completely.
[German]Since Monday, October 17, 2022, many Metro stores worldwide have been struggling with severe IT problems. I had already suspected a cyber attack on the Metro Group in a post and I had reports from Austria, from France as well as comments from German Metro customers as well as employees. However, a cyber attack remained unconfirmed so far. Now Metro AG has confirmed such an attack to heise – and on its website.
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Metro Group with IT problems
I had already reported about the IT problems at Metro Group in the blog post Cyber attack on Metro AG or just a IT break down? Austria, France, German (and more countries?) affected. Since Monday, October 17, 2022, Metro wholesales stores have been struggling with massive IT problems. No invoices or daily passes could be issued and online orders had also disappeared, Metro customers reported. A blog reader had provided me with the following photo of a Metro notice board.
Notification about IT disruption at a Metro wholesale store
The suspicion of a cyber attack has not been confirmed by company spokespersons till today (October 21, 2022). But I have had reports from German blog readers, reporting IT issues since days and some people told me, it’s a cyber attack as a root cause.
Not only Austria and France are affected, but Metro AG worldwide. In Germany, too, the same problem has existed since last Monday. No more stock or prices can be updated or checked in the store. The checkout system is still working but also sluggishly, resulting in long lines. If you want to reserve something digitally, that doesn’t work either.
One reader noted that from what he observed, the IT problems have been going on since Friday afternoon (October 14, 2022). A reader informed me on Facebook that their email systems had delivered a 442 connection Failed-Error when communicating with the Metro mail system last Monday. By the afternoon of October 19, 2022, communication with the Metro Group email system was working again – so something is happening.
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Metro confirms cyber attack
First a speaker from Metro AG confired to German IT magazine heise a cyber attack on it’s IT systems. After searching the Metro AG site today, I finally found the following statement. It says (translated in English):
Metro cyber attack confirmation (addenum: here is an English version)
T-Security Incident at METRO
METRO/MAKRO is currently experiencing a partial IT infrastructure outage for several technical services. METRO’s IT team, together with external experts, immediately launched a thorough investigation to determine the cause of the service disruption. The latest results of the analysis confirm a cyber attack on METRO systems as the cause of the IT infrastructure outage. METRO AG has informed all relevant authorities about the incident and will of course cooperate with them in every possible way.
During the operation of METRO stores and the regular availability of services, disruptions and delays may occur. The teams in the stores have quickly set up offline systems to process payments. Online orders via the web app and online store are being processed, but there may be individual delays here as well.
We will continue to analyze and monitor the situation intensively and provide updates if necessary. METRO sincerely apologizes for any inconvenience this incident may cause to customers and business partners.
So they confirmed just a cyber attack, but stay tight lipped about the details. No information, whether it’s a ransomware infection nor about a possible attack vector.
Metro AG is a listed group of wholesale companies (for purchases in the gastronomy sector). Headquartered in Düsseldorf, the group employs more than 95,000 people in 681 stores worldwide, most of them in Germany. In Germany, the company mainly operates the Metro wholesale stores. Sales are 24.8 billion euros (2020).
Over 45,000 VMware ESXi servers inventoried by Lansweeper just reached end-of-life (EOL), with VMware no longer providing software and security updates unless companies purchase an extended support contract.
Lansweeper develops asset management and discovery software that allows customers to track what hardware and software they are running on their network.
As of October 15, 2022, VMware ESXi 6.5 and VMware ESXi 6.7 reached end-of-life and will only receive technical support but no security updates, putting the software at risk of vulnerabilities.
The company analyzed data from 6,000 customers and found 79,000 installed VMware ESXi servers.
Of those servers, 36.5% (28,835) run version 6.7.0, released in April 2018, and 21.3% (16,830) are on version 6.5.0, released in November 2016. In total, there are 45,654 VMware ESXi servers reaching End of Life as of today
The findings of Lansweeper are alarming because apart from the 57% that enter a period of elevated risk, there are also another 15.8% installations that run even older versions, ranging from 3.5.0 to 5.5.0, which reached EOL quite some time ago.
In summary, right now, only about one out of four ESXi servers (26.4%) inventoried by Lansweeper are still supported and will continue to receive regular security updates until April 02, 2025.
However, in reality, the number of VMware servers reaching EOL today, is likely far greater, as this report is based only on Lansweeper’s customers.
VMWare versions detected on net scans(Lansweeper)
The technical guidance for ESXi 6.5 and 6.7 will carry on until November 15, 2023, but this concerns implementation issues, not including security risk mitigation.
The only way to ensure you can continue to use older versions securely is to apply for the two-year extended support, which needs to be purchased separately. However, this does not include updates for third-party software packages.
For more details about EOL dates on all VMware software products, check out this webpage.
What does this mean?
When a software product reaches the end-of-life date, it stops receiving regular security updates. This means that admins should have already planned ahead and upgraded all deployments to a newer release.
While it’s not unlikely that VMware will still offer some critical security patches for these older versions, it’s not guaranteed and certainly won’t release patches for all new vulnerabilities that are discovered.
Once an unsupported ESXi server has carried on for long enough without patches, it will have accumulated so many security vulnerabilities that attackers would have multiple ways to breach it.
Due to ESXi hosting virtual machines, attacking the server can potentially cause severe and wide-scale disruption to business operations, which is why ransomware gangs are so focused on targeting it.
More recently, Mandiant discovered that hackers found a new method to establish persistence on VMware ESXi hypervisors that lets them control the server and hosted VMs without being detected.
All that said, ESXi already enjoys ample attention from threat actors, so running outdated and vulnerable versions of the software would no doubt be a terrible idea.
Last modified date: 2022-10-05 Applicable Products QTS QuTS hero SED Usage Can I use different types of SEDs to create a SED secure storage pool? Yes, you can use different types of SEDs in the same SED secure storage pool.
Can I use SEDs in a normal storage pool? Yes, normal storage pools can contain SEDs. However, the SEDs would function as regular disks without self-encryption.
When creating a normal storage pool, make sure the option Create SED secure storage pool is deselected.
If I use SEDs in a normal storage pool, will the pool be locked after the NAS restarts? No, the system does not lock normal storage pools when the NAS restarts. SEDs in a normal storage pool function as regular disks without self-encryption.
Only SED secure storage pools are locked after the NAS restarts (unless the setting Auto unlock on startup is enabled).
SED Status Why is my SED’s disk status “Unlocked” even though I never activated its self-encrypting function? In QTS versions earlier than 5.0.1 and QuTS hero versions earlier than h5.0.1, only SEDs of the type TCG Opal are supported.
Starting from QTS 5.0.1 and QuTS hero h5.0.1, TCG Enterprise SEDs are also supported.
If you used any TCG Enterprise SEDs to create a normal storage pool when your NAS was running QTS versions earlier than 5.0.1 or QuTS hero versions earlier than h5.0.1, and then later upgraded your operating system to QTS 5.0.1 (or later) or QuTS hero h5.0.1 (or later), the NAS will now indicate their disk status as “Unlocked”. This does not affect the status or performance of the storage pool, and the SEDs will continue to function as regular disks.
If a TCG Enterprise SED has never been used in a storage pool, and the disk status has changed to “Unlocked” after you upgraded the NAS operating system to QTS 5.0.1 (or later) or QuTS hero h5.0.1 (or later), you can use the SED Erase function to reset the disk to factory default, and then activate self-encryption on the disk by setting an encryption password.
Resetting to Factory Default What can I do if I cannot find the PSID on my SED? SEDs usually have a PSID (physical secure ID) labeled on the disk. If you cannot find the PSID on the disk, please contact the disk manufacturer for assistance.
Why doesn’t the PSID work when I try to reset my SED? If you are unable to reset your SED to factory default using its PSID (physical secure ID), please contact the disk manufacturer for technical assistance.
If the disk manufacturer is unable to help you reset the SED, you can still use the SED as a regular disk.
Threat actors behind the relatively new Venus Ransomware are hacking into publicly-exposed Remote Desktop services to encrypt Windows devices.
Venus Ransomware appears to have begun operating in the middle of August 2022 and has since encrypted victims worldwide. However, there was another ransomware using the same encrypted file extension since 2021, but it is unclear if they are related.
BleepingComputer first learned of the ransomware from MalwareHunterTeam, who was contacted by security analyst linuxct looking for information on it.
Linuxct told BleepingComputer that the threat actors gained access to a victim’s corporate network through the Windows Remote Desktop protocol.
Another victim in the BleepingComputer forums also reported RDP being used for initial access to their network, even when using a non-standard port number for the service.
How Venus encrypts Windows devices
When executed, the Venus ransomware will attempt to terminate thirty-nine processes associated with database servers and Microsoft Office applications.
When encrypting files, the ransomware will append the .venus extension, as shown below. For example, a file called test.jpg would be encrypted and renamed test.jpg.venus.
Files encrypted by the Venus Ransomware Source: BleepingComputer
In each encrypted file, the ransomware will add a ‘goodgamer’ filemarker and other information to the end of the file. It is unclear what this additional information is at this time.
Goodgamer file marker in an encrypted file Source: BleepingComputer
The ransomware will create an HTA ransom note in the %Temp% folder that will automatically be displayed when the ransomware is finished encrypting the device.
As you can see below, this ransomware calls itself “Venus” and shares a TOX address and email address that can be used to contact the attacker to negotiate a ransom payment. At the end of the ransom note is a base64 encoded blob, which is likely the encrypted decryption key.
At this time, the Venus ransomware is fairly active, with new submissions uploaded to ID Ransomware daily.
As the ransomware appears to be targeting publicly-exposed Remote Desktop services, even those running on non-standard TCP ports, it is vital to put these services behind a firewall.
Ideally, no Remote Desktop Services should be publicly exposed on the Internet and only be accessible via a VPN
Welcome to the most complete guide on WordPress speed optimization!
This is my attempt to sum up WordPress speed + core web vitals in 1 post (it’s loooong).
I’ve constantly updated it to reflect new changes ever since I first published this 10 years ago. You have updates to things like core web vitals, plugin changelogs, and Cloudflare Enterprise happening every day. While site speed has gotten complex, the basics have stayed the same: use lightweight themes/plugins on fast servers (ideally with a performant cache plugin/CDN).
Why this tutorial is different:
First, my recommendations on tools/plugins/services are arguably better than what other people tell you to use. I’m very transparent about SiteGround’s slow TTFB and cache plugin, Kinsta’s overpriced service + lack of resources, NitroPack being blackhat, RocketCDN’s poor performance, and Elementor/Divi being slow. I’ve also written extensive reviews/tutorials on nearly every major host, cache plugin, CDN, and core web vital you can find in my nav menu.
Which is the 2nd reason it’s different: configuration guides! I have tons of them. Need help configuring FlyingPress, LiteSpeed Cache, or Perfmatters? Want to improve TTFB or LCP? Or maybe you’re wondering which Cloudflare settings to use. I have detailed guides on all those.
If you have suggestions on making this tutorial better (or you have a question), drop me a comment. I’m all ears. I’m not for hire because I spend so much time writing these guides 🙂
Chrome Dev Tools – the coverage report shows your largest CSS/JS files and where they’re loaded from (plugins + third-party code are common culprits). So many parts of speed and web vitals are related to CSS/JS and it’s best to tackle it at the source. Removing things you don’t need is better than trying to optimize it.
KeyCDN Performance Test – measure TTFB in 10 global locations. This is mainly improved with better hosting and using a performant CDN with full page caching (like APO or FlyingProxy). It also shows DNS lookup times and TLS which can be improved with a fast DNS (i.e. Cloudflare) and configuring their SSL/TLS settings.
PageSpeed Insights – most items come down to reducing or optimizing CSS, JS, fonts, images, TTFB, and above the fold content. For example, preload your LCP image and exclude it from lazy load, then move large plugins/elements below the fold so they can be delayed. Focus on recommendations in PSI’s opportunities + diagnostics sections, and monitor your core web vitals report in Search Console.
CLS Debugger – see your website’s layout shifts (CLS) on mobile/desktop in a GIF.
WP Hive – Chrome extension that lets you search the WordPress plugin repository and see whether a plugin impacts memory usage and PageSpeed scores, but only measures “out of the box settings” and not when content is added to the frontend.
Wordfence Live Traffic Report – see bots hitting your site in real-time. AhrefsBot, SemrushBot, compute.amazonaws.com and other bots can be blocked if you’re using their service. Since most bot protection services don’t block these service’s bots, you’ll need to do this manually with something like Cloudflare firewall rules.
WP-Optimize – see which plugins add database overhead and remove old tables left behind by plugins/themes you deleted. Does a better than job cache plugins with scheduled cleanups because it can keep a certain number of post revisions while removing junk (cache plugins delete them all, leaving you with no backups).
cdnperf.com + dnsperf.com – you can these as baseline for choosing a DNS/CDN provider, but it doesn’t include StackPath’s CDN (removed from cdnperf and used by RocketCDN), QUIC.cloud’s CDN or CDN (used on LiteSpeed), and other services.
Waterfall Charts – testing “scores” isn’t nearly as effective as measuring things in a Waterfall chart. Google’s video on optimizing LCP is a great resource and shows you the basics. You can find one in WebPageTest, Chrome Dev Tools, and GTmetrix.
Diagnostic Plugins – the speed plugins section lists all plugins mentioned in the guide. It includes diagnostic plugins like Query Monitor (this is probably best for finding bottlenecks), WP Server Stats, WP Hosting Benchmark, and WP Crontrol.
2. DNS
A slow DNS causes latency which is part of TTFB (and TTFB is part of LCP).
Whoever you registered your domain through is who you’re using for a DNS. GoDaddy, NameCheap, and even Amazon Route 53 (used on Kinsta) don’t perform well on dnsperf.com. Better options include Cloudflare, QUIC.cloud, or Google (if using Google Domains). I usually recommend Cloudflare since it’s free and can be used on any setup by changing nameservers.
3. Hosting
Rocket.net with their free Cloudflare Enterprise will outperform any “mainstream host” since you get 32 CPU cores + 128GB RAM, NVMe storage, Redis, and Cloudflare’s full page caching + Argo Smart Routing. I use them and average a <150ms global TTFB (or click through my posts).
Combining a good host/CDN is arguably the best way to improve TTFB (using a host with improved specs on top of Cloudflare Enterprise hits 2 birds with 1 stone).
Mainstream hosts (like SiteGround, Hostinger, and WPX) don’t have a lot of CPU/RAM, use slower SATA SSDs, and are shared hosting with strict CPU limits which force you to upgrade plans. Cloud hosting is faster, but Kinsta still uses SATA SSDs with low CPU/RAM, PHP workers, and monthly visits (Redis also costs $100/month). Cloudways Vultr HF is who I previously used, but again, they start with only 1 CPU + 1GB RAM on slower Apache servers, PHP-FPM, and GZIP.
Here are Rocket.net’s:
All plans use 32 CPU cores + 128GB RAM with NVMe (faster than SATA), Redis (better than memcached), LiteSpeed’s PHP, and Brotli (smaller compression than GZIP). They have no PHP worker limits since only about 10% of traffic hits your origin due to their Cloudflare Enterprise.
SiteGround
Hostinger
Kinsta
Cloudways Vultr HF
Rocket.net
Hosting type
Shared
Shared
Cloud
Cloud
Private cloud
Storage
SATA
SATA
SATA
NVMe
NVMe
CPU cores
Not listed
1-2
12
1
32
RAM (GB)
Not listed
.768 – 1.536
8
1
128
Object cache
Memcached
x
Redis ($100/mo)
Redis (Pro)
Redis
Server
Nginx
LiteSpeed
Nginx
Apache
Nginx
PHP processing
FastCGI
LiteSpeed
FastCGI
FPM
LiteSpeed
Compression
Brotli
Brotli
Brotli
GZIP
Brotli
CPU limits
Very common
Low memory
Low PHP workers
Average
None
Why you need Cloudflare Enterprise
Because you get Enterprise features like 270+ PoPs, prioritized routing, full page caching, HTTP/3, WAF, and image optimization. 3 problems with most CDNs are their small network (PoPs) and no full page caching or image optimization. For example, WP Rocket’s RocketCDN uses StackPath which was removed from cdnperf.com and doesn’t include image optimization with a mediocre Tbps speed of 65+. SiteGround’s CDN only has 14 PoPs. QUIC.cloud CDN (for LiteSpeed) and BunnyCDN are good, but they still don’t beat Cloudflare Enterprise. Sure, you can pay $5/mo for Cloudflare’s APO, but you’re still missing out on all other Enterprise features.
3 popular hosts with Cloudflare Enterprise
Rocket.net’s Cloudflare Enterprise is free, setup automatically, and uses full page caching (unlike Cloudways). And unlike Kinsta’s, Rocket.net has Argo Smart Routing (specifically good for WooCommerce sites), load balancing, and image optimization. Rocket.net CEO Ben Gabler also used to be StackPath’s Chief Product Officer and went as far as building Rocket.net’s data centers in the same locations as Cloudflare’s. And unlike both hosts, Rocket.net doesn’t limit PHP workers (there’s no CPU limits) and monthly visit limits are 10-25 times more than Kinsta’s.
Cloudflare Enterprise (Kinsta)
Cloudflare Enterprise (Cloudways)
Cloudflare Enterprise (Rocket.net)
CDN PoPs
270
270
270
Prioritized routing
✓
✓
✓
Full page caching
✓
x
✓
HTTP/3
✓
✓
✓
WAF
✓
✓
✓
Argo smart routing
x
✓
✓
Load balancing
x
✓
✓
Image optimization
x
✓
✓
Automatic configuration
x
x
✓
Price
Free
$5/mo (1 domain)
Free
Problems with mainstream hosts
I’ve written some pretty bad reviews about SiteGround’s slow TTFB, CPU limits, and why SG Optimizer does a poor job with core web vitals (they also control several Facebook Groups and threaten to sue people who write bad reviews). Hostinger writes fake reviews and is only cheap because you get less resources like CPU/RAM. Kinsta and WP Engine are way too expensive for how many resources, PHP workers, and monthly visits you get. Along with major incidents like WPX’s worldwide outage and SiteGround’s DNS getting blocked by Google for 4 days (both WPX and SiteGround denied responsibility). One thing is clear: most mainstream hosts appear to be more interested in profits than performance. Please do your own research before getting advice.
Getting started on Rocket.net
Step 1: Create a Rocket.net account and you’ll be prompted to add a coupon. Sign up with coupon OMM1 to get your first month for $1 (renews at $30/mo or $25/mo when paying yearly). If you sign up with my coupon or affiliate links, I get a commission which I seriously appreciate.
Step 2: Request a free migration. They did this the same day and let me review my website before it was launched with no downtime. For the record, their support is better than Kinsta’s and you can reach out to Ben Gabler or his team (via phone/chat/email) if you have questions.
Step 3: Upgrade to PHP 8.1 and ask support to install Redis (they use Redis Object Cache). These are the only things I did since Cloudflare Enterprise and backups are both automatic.
Step 4: Retest your TTFB in SpeedVitals and click through your pages to see the difference. You can also search their TrustPilot profile for people mentioning “TTFB” where they’re rated 4.9/5.
I was previously on Cloudways Vultr HF which was great, but their Cloudflare Enterprise doesn’t use full page caching (yet) and is $5/mo with annoying challenge pages. Even if their Cloudflare Enterprise was identical, Rocket.net still outperforms them with better specs like more CPU/RAM, Brotli, and LiteSpeed’s PHP (plus better support, easier to use, and usually pricing). While Cloudways is a big improvement than most hosts, you’re already spending $18/mo for Vultr HF’s lowest 1 CPU plan with Cloudflare Enterprise. At that point, the extra $7/mo you’d be spending at Rocket.net is worth it. Rocket.net’s dashboard is also much easier.
For small sites on a budget, NameHero’s Turbo Cloud plan is similar to Hostinger between LiteSpeed, cPanel, and pricing. However, NameHero’s Turbo Cloud plan has about 1.5x more resources (3 CPU + 3GB RAM) with NVMe storage. NameHero’s support/uptimes are also better shown in TrustPilot reviews. This is one the fastest setups on a budget… you get a LiteSpeed server + LiteSpeed Cache + QUIC.cloud CDN, and email hosting. The main con is their data centers are only in the US and Netherlands. If these aren’t close to your visitors, make sure to setup QUIC.cloud’s CDN which has HTML caching (ideally the paid plan which uses all 70 PoPs).
4. Page Builders
Elementor/Divi are slower than Gutenberg/Oxygen.
Since multiple PSI items are related to CSS/JS/fonts, many people are replacing them with lightweight alternatives. The last thing you want to do is use a slow page builder then install a bunch of “extra functionality plugins” which add even more CSS/JS. Don’t fall into this trap. If you don’t want to ditch your page builder completely, there are still ways you can optimize it.
Divi/Elementor add extra CSS/JS/fonts to your site.
Adding more page builder plugins can slow it down more.
GeneratePress (what I use), Kadence, Blocksy, Oxygen are faster.
If using Elementor, try the settings under Elementor → Experiments.
Same thing with Divi (Divi → Theme Options → General → Performance).
If using Astra Starter Sites, use a template built in Gutenberg (not Elementor).
Use CSS for your header/footer/sidebar (instead of bloated page builder code).
Elementor has a theme customizer setting to host fonts locally + preload them.
If you don’t use Elementor font icons, disable them or use custom icons instead.
If you don’t use elementor-dialog.js for popups, disable it (i.e. using Perfmatters).
Many page builder plugins are module-based, so disable modules you don’t use.
Simplify your design by using less widgets/columns (here’s a YouTube video on it).
If you preload critical images in FlyingPress or Perfmatters, this excludes above the fold images from lazy load and preloads them to improve LCP. However, it doesn’t work with Elementor image widgets (go through your page builder + cache plugin documentation).
Background images aren’t lazy loaded by default because they’re loaded from a separate CSS file. Some cache plugins support a lazy-bg class you can use to lazy load backgrounds.
A performant CDN with HTML caching (and other CDN features) can be the difference maker. While cdnperf.com is a good baseline, there are other things to consider.
Start by looking at their network page (you’ll see BunnyCDN’s network has more PoPs and faster a Tbps than StackPath). Also look at the features (for example, RocketCDN only serves files from the CDN and nothing else while other CDNs do a lot more than just “serving files.” Cloudflare’s dashboard has hundreds of optimizations to improve speed, security, and CPU usage. Aside from choosing a good CDN, make sure to also take advantage of everything it offers. Or just use a service like FlyingProxy/Rocket.net that integrates Cloudflare Enterprise.
Cloudflare – it’s hard to beat Cloudflare with 270+ data centers and all the robust features. Open your Cloudflare dashboard and use the recommendations below to configure settings.
Free Cloudflare Features I Recommend Using
CDN – in your DNS settings, find your domain and change the proxy status to Proxied (orange cloud). This is needed for several Cloudflare features to work.
TLS version – set minimum TLS version to 1.2 and make sure TLS 1.3 is enabled.
Firewall rules – often used to block access to wp-login, XML-RPC, and “hacky” countries. Firewalls block attacks along with unwanted requests to the server.
Bot protection – block spammy bots from hitting your server. I would also check your Wordfence live traffic report to see bots hitting your website in real time and manually block bots like AhrefsBot + SemrushBot if you don’t use them. Bot fight mode can add a JS file to your site (invisible.js) and cause PSI errors (so test this).
Brotli – this only works if your host supports Brotli, otherwise GZIP will be used.
Early hints – while the server is waiting for a response, preload/preconnect hints are sent to the browser so resources load sooner, reducing your server think time.
Browser cache TTL – 1 year is good for static sites (my blog is mostly static so this is what I use) or use 1 month for dynamic sites. This is recommended by Google and can fix serve static assets with an efficient cache policy in PageSpeed Insights.
Crawler hints – helps search engines efficiently time crawling and save resources.
Cache reserve – improves cache hit ratio by making sure specific content is being served from Cloudflare even when the content hasn’t been requested for months.
Workers – deploy code on Cloudflare’s edge servers (try the playground). Workers are serverless with automatic scaling + load balancing. Obviously involves coding knowledge and can reduce LCP by 80%. It can also be used for external cron jobs.
Cache everything page rule – most common page rule which caches HTML and improves TTFB, but I recommend APO or Super Page Cache for Cloudflare instead.
HTTP/3 – not true HTTP/3 but still a nice feature (test your site using HTTP/3 test).
0-RTT connection resumption – good for repeat visitors, latency, mobile speed.
Hotlink protection – saves bandwidth by stopping people from copying your images and using them on their own website while they’re hosted on your server.
Zaraz – offload third-party scripts to Cloudflare like Google Analytics, Facebook Pixel, chatbots, and custom HTML. But test your results against delaying these.
Monitor bandwidth/analytics – the more bandwidth you offload to Cloudflare the better. This should lighten the load on your server while reducing CPU usage.
Paid Cloudflare Features
APO – caches HTML which can improve TTFB in multiple global locations.
WAF – block unwanted requests, improve security, and reduce CPU usage.
Argo + Tiered Cache – route traffic using efficient paths with Tiered Cache.
Image optimizations – I prefer these over plugins. Between all 3 (image resizing, Mirage, Polish), you don’t have to use a bloated image optimization plugin and they usually do a better job. You have features like compression/WebP and they also have mobile optimizations like serving smaller images to reduce mobile LCP.
Signed Exchanges – improves LCP when people click links in Google’s search results via prefetching which Google says can lead to a substantial improvement.
Load Balancing – creates a failover so your traffic is re-routed from unhealthy origins to healthy origins. Can reduce things like latency, TLS, and general errors.
Cloudflare Enterprise – majors benefits include prioritized routing, more PoPs, Argo + Tiered Cache, full page caching, image optimization, and other features depending where you get it from. The easiest/cheapest way is to use a host with Cloudflare Enterprise or FlyingProxy (I recommend Rocket.net’s who even built their data centers in the same locations as Cloudflare). It’s just more thought out than Cloudways/Kinsta. You could also consider using Cloudflare Pro which has some of these features. It requires more configuration but gives you more control.
Take advantage of different caching layers your host offers
BunnyCDN – Gijo suggests Cloudflare + BunnyCDN which is what I’ve used for a long time. If you’re using FlyingPress, FlyingCDN is powered by BunnyCDN with Bunny Optimizer + geo-replication. It’s also cheaper than buying these directly through BunnyCDN and easy to setup.
QUIC.cloud – use this if you’re on LiteSpeed. You’ll want to use the standard (paid) plan since the free plan only uses 6 PoPs and doesn’t have DDoS protection. It has HTML caching which is similar to Cloudflare’s full page caching and is also needed for LSC’s image/page optimizations.
RocketCDN – uses StackPath which was removed from cdnsperf.com and has less PoPs, slower Tbps, no image optimization, no HTML caching, and no other features besides serving files from a CDN. Also isn’t “unlimited” like WP Rocket advertises since they will cut you off at some point.
SiteGround CDN – not a lot of PoPs/features and you have to use their DNS to use it (which if you remember, was blocked by Google for 4 days). I personally wouldn’t trust this with my site.
6. Cache Plugins
Let’s summarize 5 popular cache plugins in 10 lines or less.
FlyingPress – optimizes for core web vitals and real-world browsing better than the last 3. When a new core web vital update comes out (like fetchpriority resource hints), Gijo is almost always first to add it. Awesome features not found in most cache plugins: preloading critical images lets you set the number of images usually shown above the fold to exclude them from lazy load while preloading them. FlyingPress can also lazy render HTML elements, self-host YouTube placeholders, and it has a lazy-bg helper class for lazy loading background images. FlyingCDN uses BunnyCDN with Bunny Optimizer + geo-replication (great choice). The remove unused CSS feature is faster than WP Rocket’s since it loads used CSS in a separate file (instead of inline) which Perfmatters agrees is faster for visitors. Really, the main thing it doesn’t have is server-level caching. I moved from WP Rocket to FlyingPress and saw a big difference in speed.
SG Optimizer
WP Rocket
FlyingPress
Server-side caching
✓
x
x
Delay JavaScript
x
✓
✓
Remove unused CSS
x
Inline
Separate file
Critical CSS
x
✓
✓
Preload critical images
x
x
By number
Exclude above the fold images
By class
By URL
By number
Lazy load background images
x
Inline
Helper class
Fetchpriority resource hint
x
x
✓
Lazy render HTML elements
x
x
✓
Add missing image dimensions
x
✓
✓
YouTube iframe preview image
x
✓
✓
Self-host YouTube placeholder
x
x
✓
Host fonts locally
x
x
✓
Font-display: swap
x
✓
✓
Preload links
x
✓
✓
CDN (beyond Cloudflare)
SiteGround CDN
StackPath
BunnyCDN
CDN PoPs
14
60
93
CDN Tbps
N/A
65
80
Dynamic caching
✓
x
x
CDN geo-replication
x
x
✓
CDN image optimization
✓
x
✓
CDN image resizing for mobile
x
x
✓
Documented APO compatibility
x
x
✓
LiteSpeed Cache – also does a great job optimizing for web vitals and real users, but different than FlyingPress. Mainly because it should only be used on LiteSpeed, it’s free, and it has faster server-side caching. However, the settings can be complicated. While some settings are similar to FlyingPress like loading used CSS in a separate file and lazy loading HTML elements, it has its own unique features such as localizing third-party resources, ESI, guest mode, LQIP, and HTML caching through QUIC. Use LSC if you’re on a LiteSpeed host. Anything else, I’d use FlyingPress.
WP Rocket – removing unused CSS is slower for visitors and RocketCDN isn’t a good CDN. WP Rocket doesn’t self-host fonts (or even recommend it) or video placeholders. Excluding above the fold images from lazy load and preloading them individually is tedious. Still no image optimization or documented APO compatibility. While Gijo releases many new features and updates FlyingPress to address core web vital updates, it seems WP Rocket has fallen behind. Two good things about WP Rocket are automatic delaying of JavaScript and documentation.
SiteGround Optimizer – great for caching, not for web vitals. Lacks way too many features and has a history of compatibility issues the developers blame on third-party plugins/themes if you check support threads. My advice is to only use it for caching, disable everything else, then use FlyingPress or WP Rocket (just make sure page caching is only enabled in 1 plugin and disabled in the other). Of course, SiteGround will glorify their cache plugin even when it’s clearly inferior.
NitroPack – don’t use this! The only reason you get better “scores” is because it moves elements off the main-thread so they can’t be detected in speed testing tools. This leads to great (but false) scores and it doesn’t actually do a good job making your website load faster compared to other plugins. Google “NitroPack blackhat” and you’ll find plenty of articles on it.
7. Other Caching
Cache plugins are just 1 layer.
Check whether your host supports object cache (Redis/memcached), OPcache, and HTTP accelerators like Varnish/FastCGI. Most do but they need to be enabled or set up manually.
You also have CDN caching which is its own layer. All these are meant for different things and you should ideally use most (if not all) them. People get scared they’re using too much caching, but as long as you’re only using 1 type of layer (not both Redis + memcached), it’s a good thing.
OPcache – enable in your host (can help reduce CPU usage).
Browser cache – enable in your cache plugin (stores files in browsers).
HTTP accelerators – enable in your host (probably Varnish or FastCGI).
Object cache – Redis generally uses memory more efficiently than memcached and is good for large/eCommerce sites. Once it’s enabled in your host, you’ll connect it your site using a plugin (i.e. LiteSpeed Cache, W3 Total Cache, SG Optimizer, WP Redis). Check your host’s documentation/support on which plugin is best. For example, Rocket.net requires you to install the WP Redis plugin while Cloudways requires you to install the Redis addon.
CDN cache – APO is not the same as a cache everything page rule or the Super Page Cache plugin. QUIC also does HTML caching, then there are services that include Cloudflare’s full page cache like Rocket.net’s Cloudflare Enterprise, FlyingProxy, and SiteGround Optimizer. The key thing is that you’re caching HTML somewhere as it can significantly improve TTFB.
Take advantage of different caching layers your host offers
8. Plugins
Watch out for plugins that:
Add CSS/JS to the frontend – use the Chrome Dev Tools coverage report to see which plugins add CSS and JS. This includes plugins that inject third-party JavaScript or fonts.
Increase CPU usage – common with plugins that collect “statistics” like Wordfence’s live traffic report, Query Monitor, and Broken Link Checker. But can really be from any plugin. WP Hive tells you if a plugin increases memory usage when browsing the WP plugin repo.
Add database bloat – use WP-Optimize to see which plugins (or specific plugin modules) add the most database overhead. This is explained more in this guide’s database section.
Load above the fold – slow plugins are bad enough, but loading them above the fold is even worse. When plugins load below the fold, you can delay them (i.e. comment plugins).
Use jQuery – Perfmatters has a script manager setting to show dependencies. Once it’s enabled, head to the script manager → jQuery and it shows you all plugins using jQuery. Felix Arntz wrote an article on how removing jQuery can reduce JavaScript by up to 80%.
Security – no security plugin (Cloudflare, firewall, etc).
Sliders – Soliloquy or MetaSlider (but ideally no sliders).
Analytics – call me crazy but I only use Google Search Console.
SEO – Rank Math or SEOPress (but most SEO plugins use jQuery).
CSS – need custom styling or even a table of contents? Just use CSS.
Backups – hosting backups or a lightweight alternative like UpdraftPlus.
In Query Monitor, the “queries by component” section shows your slow plugins. You can also use my list of 75+ common slow plugins. Finally, delete all plugins you’re not using (as well as their database tables in WP-Optimize), and disable plugin features/modules you’re not using.
Plugin
Category
Memory Impact
PageSpeed Impact
All In One SEO
SEO
x
x
Broken Link Checker
SEO
x
✓
Disqus
Comments
✓
x
Divi Builder
Page Builder
x
x
Elementor
Page Builder
x
x
Elementor Premium Addons
Page Builder
✓
x
Elementor Pro
Page Builder
x
x
Elementor Ultimate Addons
Page Builder
✓
x
JetElements
Page Builder
x
x
Jetpack
Security
x
x
NextGEN Gallery
Gallery
x
x
Popup Builder
Popup
x
x
Site Kit by Google
Analytics
x
✓
Slider Revolution
Slider
x
x
Social Media Share Buttons
Social Sharing
✓
x
WooCommerce
WooCommerce
x
x
Wordfence
Security
x
✓
wpDiscuz
Comments
x
x
WPML
Translate
x
x
Yoast SEO
SEO
x
✓
9. CSS + JavaScript
Probably the #1 reason for poor core web vitals.
New Optimizations
Remove unused CSS – WP Rocket’s method of loading used CSS inline is slower for visitors but better for scores. You should ideally use FlyingPress, LiteSpeed Cache, or Perfmatters for this which loads used CSS in a separate file so it can be cached and doesn’t increase HTML size. You should only be using 1 plugin for this. If you’re not using an optimization plugin that does this, try DeBloat or PurifyCSS.
Remove Gutenberg CSS – if you don’t use Gutenberg’s block library (i.e. you’re using classic editor), you can remove Gutenberg’s CSS which is loaded by default.
Asset unloading plugins – remove CSS/JS (or entire plugins) from specific pages/posts where they don’t need to load. Common examples are only loading contact forms on the contact page, only loading social sharing plugins on posts, and disabling WooCommerce plugins where they’re not used. You can also disable specific files like jQuery and elementor-dialog if you don’t use them. I recommend Perfmatters especially if you’re using WP Rocket or SiteGround Optimizer because it has many optimizations not found in these plugins. Be sure to use test mode and dependencies in your script manager settings. For a free plugin, try Asset CleanUp.
Critical CSS – loads above the fold CSS immediately which improves LCP. Most cache plugins do this while others (like SG Optimizer) don’t. If you make changes to stylesheets or custom CSS, regenerate critical CSS so it’s current with your site.
Load CSS/JS non render-blocking – both deferring JavaScript and critical CSS help serve resources non render-blocking. Make sure they work in your cache plugin and exclude files from defer if they break your site. Or try Async JavaScript.
Don’t combine – should almost always be off especially on big sites or on HTTP/2.
Optimizations Covered In Other Sections
Page builders – Elementor/Divi add extra CSS/JS which can be optimized with their built-in performance settings, coding your header/footer/sidebar in CSS, disabling Elementor fonts/dialog, lazy loading background images in CSS, etc.
Plugins – just look at the screenshot below (plugins are obviously a major factor).
Third-party code – hosting files locally, delaying JavaScript, and using a smaller GA tracking code can reduce its size or delay so it doesn’t impact initial load times.
Font Icons – disable these if you don’t use them or use Elementor’s custom icons.
WooCommerce – disable scripts/styles on non-eCommerce content and disable Woo plugins where they don’t need to load (many load across the entire website).
This is anything on your site that has to pull info from a third-party domain (like Google Fonts, Google Analytics tracking code, or an embedded YouTube video). It’s a common reason for JS-related errors in PSI. Luckily, most of it can be optimized especially if it’s shown below the fold.
Step 1: Host files locally – some third-party code can be hosted locally (see the table below). LiteSpeed Cache can localize resources, FlyingPress can host fonts/YouTube thumbnails locally, Perfmatters does fonts and analytics, and WP Rocket does nothing.
Third-Party Code
URL(s)
Plugins To Host It Locally
Google Fonts
fonts.gstatic.com
Most optimization plugins, Elementor, OMGF
Google Analytics
google-analytics.com
Flying Analytics, Perfmatters
Gravatars
gravatar.com
Simple Local Avatar
YouTube Thumbnails
i.ytimg.com
FlyingPress, WP YouTube Lyte
Step 2: Delay JavaScript – for third-party code that can’t be hosted locally, delay its JavaScript if it’s loading below the fold (you can also delay plugins loading below the fold). WP Rocket does this automatically while other cache plugins make you add files manually. If your cache plugin doesn’t support this, use Perfmatters or Flying Scripts. In these, you’ll set a timeout period and can increase this if you’re not seeing good results. You can try offloading third-party code to Cloudflare Zaraz, but I prefer delaying its JS.
Step 3: Prefetch or preconnect everything else – for all third-party code that can’t be hosted locally or delayed, add a DNS prefetch resource hint. Preconnect is usually only used for CDN URLs (not needed for Cloudflare), and third-party fonts (should be hosted locally). Or YouTube if you can’t eliminate requests using video optimizations in step #13.
Google Analytics – Perfmatters + Flying Analytics can use a minimal analytics tracking code that’s just 1.5 KB. Perfmatters can also prevent a Doubleclick request by disabling display features, but both these should only be used if you don’t need certain data in GA.
Avoid overtracking – one of the most common “mistakes” I see is sites using too many tracking tools: Analytics, Tag Manager, Heatmaps, Pixel, etc. Do you really need them all?
11. Fonts
Probably your largest files after CSS/JS.
Your GTmetrix Waterfall chart shows font load times, number of requests, and whether they’re served locally or from a third-party domain like fonts.gstatic.com or use.fontawesome.com. Be sure to keep tabs on your Waterfall chart as you make optimizations. Fonts can also cause FOIT and FOUT which cause layout shifts. A few simple tweaks can make your fonts load much faster.
Reduce font families, weights, icons – try to only use 1 font family and only load the weights you actually use. Disable Font Awesome and Eicons if you don’t use them (Elementor has a tutorial on this). Some fonts also have larger file sizes than others.
Use WOFF2 – the most lightweight/universal format which is faster than .ttf and .otf.
Host locally – if your fonts are being served from fonts.gstatic.com, host them locally.
Preload – fonts should be preloaded when they load above the fold or used in CSS files. Most cache/optimization plugins require you to manually add font files (and if there’s a crossorigin option like in Perfmatters, it should be used for fonts). Elementor hosts fonts locally and preloads them under Theme Customizer → Performance. PSI used to tell you which fonts to preload in “preload key requests” but I don’t think they do this anymore.
Add font-display: optional – if you need to “ensure text remains visible during webfont load,” add font-display: optional to your font’s CSS. This is recommended by Google for the fastest performance while preventing layout shifts. It delays loading text up to 100ms. As of writing this, most plugins only support swap found in Elementor, Perfmatters, and most cache plugins. To use optional, you need to add it manually to your font’s CSS, use WP Foft Loader, or use swap until your optimization plugin supports optional. Preloading fonts that use font-display: optional completely eliminates layout shifts (FOIT) from fonts.
System fonts – system fonts generate 0 requests and are obviously best for speed, but even for someone who obsesses over performance, I’d rather have a better looking font.
Use custom Icons for Elementor – replace Font Awesome and Eicons with custom icons.
Serve Google Fonts from Cloudflare Workers – I’ll leave this here if you want to dive in.
12. Images
There are 7 PSI items related to image optimization, and that doesn’t even cover everything.
Preload critical images and exclude them from lazy load – above the fold content should load immediately which is a big factor of LCP. Instead of delaying images with lazy load, you want the browser to download them immediately by using preload. The easiest way to do this (by far) is “preload critical images” in FlyingPress or Perfmatters. Instead of manually excluding/preloading above the fold images on every single page/post (because they’re usually different), you will set the number of images usually shown above the fold. In my case, it’s 3. This will preload your top 3 images while excluding them from lazy load. Currently, FlyingPress is the only cache plugin I know that supports fetchpriority which is recommended by Google to set things like your LCP image to “high priority.” Props to Gijo.
Exclude above the fold images from lazy load and preload them
LCP image – your most important image to optimize for lower LCP (shown in PSI).
Background images – page builders serve background images in their CSS and won’t be lazy loaded, leading to ‘defer offscreen images’ errors. Some cache plugins have a lazy-bg helper class, Perfmatters has a CSS background images setting, and WP Rocket makes you move them to inline HTML. Check the documentation in your cache/image optimization plugin on how to lazy load them. You can also use Optimal or add a helper class yourself.
Image CDNs – I use Cloudflare for image optimization but Bunny Optimizer and QUIC are good too. They usually do a better job than plugins (and it’s 1 less plugin on your website).
Resize images for mobile – make sure your image optimization plugin (or image CDN) serves smaller images to mobile which should also improve your LCP on mobile. This is the “image resizing” feature in Cloudflare, or you could use ShortPixel Adaptive Images.
Properly size images – resize large images to be smaller. My blog is 765px width so I crop/resize blog images to that size (the Zoom Chrome Extension is handy for getting the perfect dimensions when taking screenshots). I always recommend creating an “image dimensions cheat sheet” so you know the size of your blog, featured, sidebar images, etc.
WebP – faster than JPEG/PNG and most image optimization plugins or CDNs can do this.
Compression – Lighthouse test images at 85% so that’s usually a good compression level.
CSS sprites – combines multiple small/decorative images into 1 image so it only creates 1 request. My old homepage used a CSS sprite and it was very fast. You can do it for sections like “featured on” where you show a bunch of logos. You would use a CSS sprite generator.
Specify dimensions – most cache plugins can “add missing dimensions” otherwise you would need to add a width/height to the image’s HTML or CSS. This prevents layout shifts.
Downgrade quality on slow connections – services like Cloudflare Mirage + Optimole serve low quality images on slow connections until a faster connection can be accessed.
Hotlink protection – stops people from using your images when they’re hosted on your server and saves bandwidth. Common with sites using high quality images or if people copy your content. Can be enabled in your host or by using Cloudflare’s hotlink protection.
Low quality images placeholders (LQIP) – if you’re using QUIC.cloud on LiteSpeed, these can prevent layout shifts but you need to make sure you’re doing it right or it will look bad.
13. Videos
Unless videos are optimized, they will probably be the slowest thing on a page.
While most cache plugins lazy load videos and replace iframes with a preview image, FlyingPress and WP YouTube Lyte are some of the only plugins that optimize placeholders.
Lazy load videos – done in cache plugins, Perfmatters, or try WP YouTube Lyte.
Replace YouTube iframes with preview images – the iframe (which is the heaviest element of the video) is only loaded once your visitors actually click the play button.
Self-host YouTube placeholders – FlyingPress and WP YouTube Lyte can self-host placeholders to prevent i.ytimg.com requests shown in your “third-party code” report.
Preconnect – if you’re not able to make the optimizations above and you still have third-party domains loading from YouTube, you can preconnect domains from youtube.com, i.ytimg.com, and Roboto which is currently being used as the font in the YouTube player.
View your “longest main-threads tasks” report in PageSpeed Insights and optimize those files. LCP includes 4 sub-parts and Google’s YouTube video is a nice resource for optimizing each one.
Most LCP recommendations are scattered in this guide, so I’ll just go over them briefly.
Exclude above the fold images from lazy load – you should never lazy load, delay, or defer anything that loads above the fold because this content should load immediately, which is why you should also use preload hints to help browsers download them faster.
Prioritize above the fold images – preload above the fold images (or use fetchpriority). PSI shows your largest contentful paint image which is the most important to optimize.
Reduce CSS, JS, font sizes – a big part of reducing load time is reducing their file sizes.
Reduce TTFB – 40% of LCP can usually be improved with a better hosting + CDN setup.
Eliminate render-blocking CSS/JS – render-blocking resources add delay (see video).
Use font-display: optional – if fonts aren’t loaded properly, they can also add delay.
Lazy render HTML elements – allows browsers to focus on the above the fold content.
Preload, preconnect, prefetch – hints browsers to download specific resources faster.
Increase cache expiration – also mentioned by Google (Cloudflare browser cache TTL).
Choose the right cache plugin/settings – some have better optimizations than others.
Enable Signed Exchanges (SXGs) – this is found in Cloudflare (Speed → Optimization).
Use Cloudflare Workers – Google Engineer used Workers to improve LCP by about 80%.
Move plugin content, ads, animations below the fold – that way, they can be delayed.
16. CLS
Layout shifts happen when things jump around while the page is loading.
You can use Google’s layout shift debugger to see these in a GIF. PSI also has an “avoid large layout shifts” item showing you which sections on your website contribute the most to CLS. Even with these recommendations, it’s hard to know why the section is causing a layout shift.
Change font-display to swap or optional – do this if you see “ensure text remains visible during webfont load.” As shown in section #11, font-display: optional is the best method.
Problems with loading CSS asynchronously – this is a setting in cache plugins that can add layout shifts caused by FOUC (flash of unstyled content). Ideally use the “remove unused CSS” method instead. If this breaks your site and you default back to loading CSS asynchronously, make sure you exclude problematic files causing FOUC, ensure critical CSS is working, and always regenerate critical CSS after updating stylesheets/custom CSS.
Preload fonts – preloading fonts eliminates layout shifts when they use display: optional.
Specify dimensions of images, videos, iframes, ads – the first 3 are easy (make sure a width and height are specified in images). Ads and other dynamic content should have reserved space by placing it in a div code. The width/height should be the ad’s largest size.
Use CSS transform in animations – not a fan of animations but here’s documentation.
Use separate mobile cache (when it makes sense) – if your mobile site is different than desktop and you’re not using a separate mobile cache, it can cause layout shifts. However, you’ll need to check your cache plugin’s documentation on when to use (and not use) this.
Change cookie notice plugin – search your plugin’s support thread. It’s been reported some cookie plugins cause layout shifts. I recommend Gijo’s solution or this Cookie plugin.
17. Preload, Prefetch, Preconnect
These help browsers download high priority resources faster.
They prioritize above the fold content (preload + fetchpriority). Preload is also used in Cloudflare’s Early Hints and for downloading internal pages in the background so they load faster when visitors click them (link preloading + Flying Pages). Prefetch + preconnect help establish early connections to third-party domains if resources aren’t already being delayed.
Preload – commonly used for above the fold images (this can also be a WebP image) but can also be used for CSS/JS (i.e. the block library), videos, audio, Cloudflare workers, and other files.
Fetchpriority – similar to preload only assigns a priority (low, high, auto). For example, if you have a large LCP image, you would assign that image’s priority to “high.” But if you have an image carousel that’s loading above the fold, you could assign the images with a low priority. FlyingPress is the only plugin I know currently supporting fetchpriority shown in the changelog.
<img src="lcp-image.webp" fetchpriority="high">
Link preloading – there’s 2 main types: preloading links in the viewport so internal links in the immediate content load faster when clicked (supported by Flying Pages and FlyingPress). And “link preloading” where users hover over any internal link (or touch it on mobile), and the page will download in the background so by the time they actually click it, it appears to load instantly (found in cache plugins like WP Rocket). While neither improves scores, both improve perceived load time. Just be careful… preloading too many pages in the background will increase CPU usage especially if you have something like a WooCommerce store with internal links in images. If visitors are hovering over product images, this will cause lots of pages to download. Not good!
DNS Prefetch – this helps browsers anticipate third-party domains by performing a DNS lookup, but usually not needed since third-party domains should be hosted locally or delayed.
Preconnect – establishes early connections to important third-party domains. Common with CDN URLs and third-party fonts like fonts.gstatic.com, use.fontawesome.com, and use.typekit. Most cache plugins add preconnect automatically when you add a CDN URL or when enabling “Google Font Optimization” (or a similar setting), but you’ll want to check their documentation.
You can use Perfmatters or Pre* Party if your optimization plugin doesn’t support a specific resource hint
18. Database
There’s usually 3 problems with using your cache plugin to clean your database:
It can’t take database backups.
It can’t remove database tables left behind by old plugins.
It deletes all post revisions, but you may want to keep a few.
That’s why I recommend WP Optimize for database cleanups. Go through your database tables and look for tables that are not installed or inactive. You can delete these if you don’t plan on using the plugin (or theme) again since they will usually store info in the database for future use.
Certain plugin modules/features can also add lots of overhead especially if they collect data. Rank Math’s Google Analytics module adds lots of overhead, so consider disabling this Rank Math module and getting your analytics data directly from the Google Analytics website instead.
For ongoing database cleanup, WP-Optimize removes everything most cache plugins do, but it lets you keep a certain amount of post revisions so you have backups (I recommend 5-10). You can also connect UpdraftPlus which takes a database backup before scheduled optimizations.
19. Background Tasks
Background tasks can bog down your server and increase CPU usage.
These are common with cache plugins (preloading + automatic cache clearing), plugins that collect stats or create autoloads, and even WordPress core (Heartbeat, autosaves, pingbacks). Many of these can be disabled, limited, or scheduled during non-peak hours using a cron job.
Control Preloading – the preloading in cache plugins is infamous for increasing CPU usage (WP Rocket’s preloading, LSC crawler, SG Optimizer’s preheat cache, etc). The first step is changing settings to only preload important sitemap URLs (i.e. page-sitemap.com + post-sitemap.com) instead of the full sitemap. Next, you can increase the preload interval.
Only preload important sitemap URLs (not the full sitemap)
Automatic cache clearing – there are specific actions that trigger your entire cache to be cleared (and when the cache lifespan expires). Instead of constantly clearing cache with these actions, disable automatic cache clearing and use a cron job to clear it at a specific time (once at night). It’s best to use a cron job for both cache clearing + cache preloading.
Disable WP-Cron – using an external cron to schedule tasks like the 2 items above helps reduce CPU usage. The first step is to add the code below your wp-config.php file. Next, setup a real cron job in your host, Cloudflare, or using a third-party service like EasyCron. Some hosts have specific instructions for adding a cron job, so check their documentation.
Scheduling tasks using cron jobs for 5-10 minutes can reduce CPU usage
Remove unused CSS – decrease WP Rocket’s batch size and increase the cron interval.
Link preloading – some cache plugins can “preload links” which sounds like a good idea because when users hover over a link, that page downloads in the background to make it load faster by the time users actually click it. But if your website has lots of links (such as a WooCommerce store with links in the product images), you’ll want to leave this setting off.
Plugins – think of Query Monitor, Wordfence’s live traffic report, and backup/statistic plugins (they all run background tasks). You might be able schedule these, disable specific features in plugins, or delete the plugin completely. Plugins/themes can also leave behind autoloaded data when you delete them which can be cleaned up in the wp_options table.
Autosaves – when you’re editing a post, WordPress autosaves a draft every minute. You can use a simple line of code (or Perfmatters) to increase this to something like 5 minutes.
define('AUTOSAVE_INTERVAL', 300); // seconds
Heartbeat – called every 15s and can usually be disabled in the frontend/backend, then limited in the post editor since you probably want to keep features there (like autosaves).
Pingbacks – disable pingbacks since you don’t want a notification every time you add an internal link. You may want to leave trackbacks on to help notify blogs you linked to them.
Post revisions – stored every time you hit save, publish, or update and accumulate over time. You can limit revisions in some optimization plugins, manually with code, or use WP-Optimize to run scheduled database cleanups while keeping a certain number of revisions.
define( 'WP_POST_REVISIONS', 10 );
Plugin data sharing – disable in plugins to save a little resources, sorry plugin developers!
Bots – blocking spam bots and using Cloudflare’s crawler hints saves resources from bots.
Comment spam – I use Antispam Bee and blacklist these words in the Discussion settings.
Hosting features – WP Johnny has nice tips on disabling unused services in your hosting account like the DNS, email, FTP/SFTP, proxies, or other services if you’re not using them.
Bloat removal plugins – using plugins like Unbloater + Disable WooCommerce Bloat help.
20. Mobile
Poor mobile scores in PSI is a common issue. Most desktop optimizations transfer over to mobile so start with “general optimizations” first. Otherwise, here are mobile-specific tips.
Resize images for mobile – image CDNs and adaptive image plugins do this.
Reduce latency – use a faster DNS, faster TLS versions, and Cloudflare’s 0-RTT.
Replace sliders/galleries with static images – use responsive editing to do this.
Remove unused CSS/JS – Perfmatters can disable unused CSS/JS by device type.
Don’t use AMP – lots of challenges and most WordPress users agree not to use it.
Fix mobile layout shifts – Google’s layout shift debugger tests mobile layout shifts.
Use mobile caching – enable this in your cache plugin or use one that supports this.
Know when to use separate mobile cache – check your cache plugin documentation.
Downgrade image quality on slow connections – try Cloudflare Mirage or Optimole.
Check your responsiveness – even if you use a responsive theme, check this manually.
Add a “load more comments” button on mobile – helps if you have lots of comments.
Most image CDNs serve smaller images to mobile (but not RocketCDN)Disable specific files/plugins from loading on mobile in Perfmatters
21. WooCommerce
WooCommerce sites often have more plugins, scripts, styles, and are more resource-hungry than static sites. You will need to optimize your website even more if you want good results.
Hosting – wphostingbenchmarks.com ran tests for multiple WooCommerce hosts, although I think there are much better options than the ones tested (I would personally lean towards something like Rocket.net, GridPane, RunCloud). Obviously very important.
Remove WooCommerce admin bloat – Disable WooCommerce Bloat is good for this.
Cloudflare Argo + Tiered Cache – specifically good for speeding up dynamic requests.
Redis – also specifically good for WooCommerce (especially Redis Object Cache Pro).
Go easy on WooCommerce Extensions – just like other plugins, be minimal with these.
Unload WooCommerce plugins – Woo plugins are infamously bad with loading across your entire site. Use your asset unloading plugin to disable them where they’re not used.
Use Cloudflare firewall rules (i.e. only access wp-login from your IP).
Disable file editing to prevent hackers from editing theme/plugin files.
Follow security-related social media accounts like Cloudflare/Wordfence.
Check for known vulnerabilities before updating things (especially plugins).
23. PHP Version
Only 7% of websites use PHP 8.
Come on y’all, you already know higher PHP versions are faster and more secure. Google “update PHP version [your host]” and you’ll find instructions. If updating breaks your site, just revert back to your older version (or remove incompatible plugins that aren’t maintained well).
PHP version used by WordPress sites (source: WordPress stats)
24. Make Sure Optimizations Are Working
You set things up, but are they working? Make sure they are.
Caching – cache plugins should have documentation to check if the caching is working.
Redis/memcached – LiteSpeed Cache’s connection test and most Redis plugins tell you.
Confirm Redis is working (screenshot is in LiteSpeed Cache)
CDN Analytics – how many requests are you blocking from bots, hotlink protection, and WAF? What is your cache hit ratio (hopefully around 90%)? CDN analytics are very useful.
Dr. Flare – Chrome Extension to view tons of Cloudflare stats like your cache hit ratio, uncached requests, non-Cloudflare requests, how much % was reduced by Polish/Minify.
CDN rewrites – are your files actually being served from your CDN? Check your CDN Analytics, Dr. Flare, or view your source code to make sure files are being served from the CDN when using a CDN URL, like this: cdn.mywebsite.com/wp-content/uploads/logo.png. If you’re using BunnyCDN, you may be able to serve more files from BunnyCDN by adding your CDN URL to your cache plugin on top of using BunnyCDN’s plugin. It worked for me.
APO – verify Cloudflare’s APO is working by testing your website in uptrends.com then making sure headers exactly match with what Cloudflare shows in the documentation.
Confirm APO is working by checking headers
Asynchronous CSS – if you’re using this, cache plugins should also have documentation.
External cron jobs – check the logs in your hosting account to make sure these are firing.
Waterfall charts – after each optimization, you should ideally check its impact using a Waterfall chart (better than running another PageSpeed Insights test and testing scores).
Clear cache – you may need to clear cache or regenerate critical CSS to see your changes.
Obviously you don’t need all these especially if you’re using a cache/optimization plugin that already does some of these, Cloudflare image optimizations, or you can code things manually.
Plugins like Perfmatters have great documentation.
Gijo Varghese and WP Johnny also put on quality articles.
My other articles (if you liked this one, I have plenty more).
Hire Help
BDKamol – Pronaya mainly works with Gutenberg, WooCommerce, and Genesis. He’s been helping me for over 10 years even when I launched my first website and had no visitors. He points me in the right direction and was a key part in launching my new blog, helping me with things like custom coding, CSS styling, theme/plugin recommendations, etc. Pronaya lives in Bangladesh and his communication (and my trust in him) are 100%.
WP Johnny – he’s a busy guy but you can try hiring him and his team. I was lucky enough to have him help me remove my page builder (which I regret using in the first place and should have known better). While the work is great, it can take awhile to get things done.
WP Fix It – hired them once to improve issues related to core web vitals. While I was very happy with the work, they closed my tickets without notice saying the project was done, even when I told them I would pay more since truly fixing the issues required more work.
27. My Setup
This will cost about $500/year.
It assumes you already have a lightweight theme (i.e. GeneratePress/Kadence) and pay yearly for Rocket.net since you get 2 months free. It also assumes you’re using Rocket.net’s lower $25/mo plan (I pay $50/mo for the Business plan). For my site, this is the best setup I’ve found.
My blog costs around $800/year which is a lot cheaper than I was paying (mainly because hosting gets expensive as you scale). Scaling on Rocket.net is reasonable since monthly visits and RAM are both 10x Kinsta’s and there’s no PHP worker limits since only about 10% of traffic hits the origin (due to Ben Gabler’s Cloudflare Enterprise setup who I suggest reaching out to).
LiteSpeed is also solid and can be cheaper since LiteSpeed Cache is free and email hosting is often included. Check out NameHero, ChemiCloud, and Scala (they seem to have good specs and TrustPilot reviews). RunCloud, GridPane, and JohnnyVPS are probably best for larger sites.
Cloudways is who I was using. I still think they’re better than most hosts but it gets expensive with all the add-ons, they use Apache servers, and Cloudflare Enterprise + Breeze need work.
Fortinet recently patched a critical authentication bypass vulnerability in their FortiOS, FortiProxy, and FortiSwitchManager projects (CVE-2022-40684). This vulnerability gives an attacker the ability to login as an administrator on the affected system. To demonstrate the vulnerability in this writeup, we will be using FortiOS version 7.2.1
POC
Let’s examine the inner workings of this vulnerability. You can find our POC here. The vulnerability is used below to add an SSH key to the admin user, enabling an attacker to SSH into the effected system as admin.
FortiOS exposes a management web portal that allows a user configure the system. Additionally, a user can SSH into the system which exposes a locked down CLI interface. Our first step after familiarizing ourselves with the system was to diff the vulnerable firmware with the patched firmware.
Firmware Examination
We obtained a VMware zip file of the firmware which contained two vmdk files. First, we examined the vmdk files with virt-filesystems and mounted them with guestmount:
Interestingly, attempting to decompress the xz files fail with corruption errors:
$>xz --decompress *.xz
xz: bin.tar.xz: Compressed data is corrupt
xz: migadmin.tar.xz: Compressed data is corrupt
xz: node-scripts.tar.xz: Compressed data is corrupt
xz: usr.tar.xz: Compressed data is corrupt
Its unclear if this is an attempt at obfuscation, but we find a version of xz in the sbin folder of the firmware. We can’t run it as is, but we can patch its linker to point to our system linker to finally decompress the files:
$>xz --decompress *.xz
xz: bin.tar.xz: Compressed data is corrupt
xz: migadmin.tar.xz: Compressed data is corrupt
xz: node-scripts.tar.xz: Compressed data is corrupt
xz: usr.tar.xz: Compressed data is corrupt
$>find . -name xz
./sbin/xz
$>./sbin/xz --decompress *.xz
bash: ./sbin/xz: No such file or directory
$>file ./sbin/xz
./sbin/xz: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /fortidev/lib64/ld-linux-x86-64.so.2, BuildID[sha1]=eef5d20a9f8760df951ed122a5faf4de86a7128a, for GNU/Linux 3.2.0, stripped
$>patchelf --set-interpreter /lib64/ld-linux-x86-64.so.2 sbin/xz
$>./sbin/xz --decompress *.xz
$>ls *.tar
bin.tar migadmin.tar node-scripts.tar usr.tar
Next, we untar the files and begin examining their contents. We find /bin contains a large collection of binaries, many of which are symlinks to /bin/init. The migadmin folder appears to contain the frontend web code for the administrative interface. The node-scripts folder appears to contain a NodeJs backend for the administrative interface. Lastly, the usr folder contains a libaries folder and an apache2 configuration folder.
The Patch
We apply the same steps to firmware version 7.2.2 to enable diffing of the filesystems. In the bin folder, we find the large init binary has changed and in the node-scripts folder we find the index.js file has changed:
index.js diff
This diff shows that the httpsd proxy handler explicitly sets the forwarded, x-forwarded-vdom, and x-forwarded-cert headers. This gives us a hint as to where to start looking for clues on how to exploit this vulnerability.
HTTPSD and Apache Handlers
After some searching, we discover that the init binary we mentioned earlier contains some strings matching the headers in the NodeJs diff. This init binary is rather large and appears to have a lot of functionality including Apache hooks and handlers for various management REST API endpoints. To aid in our research, we SSH’d into the system and enabled debug output for the httpsd process:
fortios_7_2_1 # diagnose debug enable
fortios_7_2_1 # diagnose debug application httpsd -1
Debug messages will be on for 5 minutes.
fortios_7_2_1 # diagnose debug cli 8
Debug messages will be on for 5 minutes.
While investigating the forwarded header, we find an apache access_check_ex hook that parses the header, extracts the for and by fields, and attaches them to the Apache request_rec structure. You can see that the for field allows us to set the client_ip field on the request record’s connection.
forwarded header parsing
Additionally, we see a log message that mentioned which handler is used for a particular request.
After searching for the handler string, we find an array of handlers in the init binary:
hander array
After investigating some of the handlers, we find that many of them make a call to a function we named api_check_access:
api_check_access
We were immediately drawn to api_check_access_for_trusted_source which first checks if the vdom socket option is trusted, but then falls through to a function we called is_trusted_ip_and_user_agent.
is_trusted_ip_and_user_agent
You can see that this function checks that the client_ip is “127.0.01” and that the User-Agent header matches the second parameter. This function gets called with two possible parameters: “Node.js” and “Report Runner”. The “Node.js” path seems to perform some additional validation, but using “Report Runner” allows us to bypass authentication and perform API requests!
Weaponization
The ability to make unauthenticated request to the the REST API is extremely powerful. However, we noticed that we could not add or change the password for the admin user. To get around this we updated the admin users SSH-keys to allow us to SSH to the target as admin. See our original announcement.
Summary
To wrap things up here is an overview of the necessary conditions of a request for exploiting this vulnerabilty:
Using the Fowarded header an attacker is able to set the client_ip to “127.0.0.1”.
The “trusted access” authentication check verifies that the client_ip is “127.0.0.1” and the User-Agent is “Report Runner” both of which are under attacker control.
Any HTTP requests to the management interface of the system that match the conditions above should be cause for concern. An attacker can use this vulnerability to do just about anything they want to the vulnerable system. This includes changing network configurations, adding new users, and initiating packet captures. Note that this is not the only way to exploit this vulnerability and there may be other sets of conditions that work. For instance, a modified version of this exploit uses the User-Agent “Node.js”. This exploit seems to follow a trend among recently discovered enterprise software vulnerabilities where HTTP headers are improperly validated or overly trusted. We have seen this in recent F5 and VMware vulnerabilities.
A vulnerability in Siemens Simatic programmable logic controller (PLC) can be exploited to retrieve the hard-coded, global private cryptographic keys and seize control of the devices.
“An attacker can use these keys to perform multiple advanced attacks against Siemens SIMATIC devices and the related TIA Portal, while bypassing all four of its access level protections,” industrial cybersecurity company Claroty said in a new report.
“A malicious actor could use this secret information to compromise the entire SIMATIC S7-1200/1500 product line in an irreparable way.”
The critical vulnerability, assigned the identifier CVE-2022-38465, is rated 9.3 on the CVSS scoring scale and has been addressed by Siemens as part of security updates issued on October 11, 2022.
The list of impacted products and versions is below –
SIMATIC Drive Controller family (all versions before 2.9.2)
SIMATIC ET 200SP Open Controller CPU 1515SP PC2, including SIPLUS variants (all versions before 21.9)
SIMATIC ET 200SP Open Controller CPU 1515SP PC, including SIPLUS variants (all versions)
SIMATIC S7-1200 CPU family, including SIPLUS variants (all versions before 4.5.0)
SIMATIC S7-1500 CPU family, including related ET200 CPUs and SIPLUS variants (all versions before V2.9.2)
SIMATIC S7-1500 Software Controller (all versions before 21.9), and
SIMATIC S7-PLCSIM Advanced (all versions before 4.0)
Claroty said it was able to get read and write privileges to the controller by exploiting a previously disclosed flaw in Siemens PLCs (CVE-2020-15782), allowing for the recovery of the private key.
Doing so would not only permit an attacker to circumvent access controls and override native code, but also obtain full control over every PLC per affected Siemens product line.
CVE-2022-38465 mirrors another severe shortcoming that was identified in Rockwell Automation PLCs (CVE-2021-22681) last year and which could have enabled an adversary to remotely connect to the controller, and upload malicious code, download information from the PLC, or install new firmware.
“The vulnerability lies in the fact that Studio 5000 Logix Designer software may allow a secret cryptographic key to be discovered,” Claroty noted in February 2021.
As workarounds and mitigations, Siemens is recommending customers to use legacy PG/PC and HMI communications only in trusted network environments and secure access to TIA Portal and CPU to prevent unauthorized connections.
The German industrial manufacturing company has also taken the step of encrypting the communications between engineering stations, PLCs and HMI panels with Transport Layer Security (TLS) in TIA Portal version 17, while warning that the “likelihood of malicious actors misusing the global private key as increasing.”
The findings are the latest in a series of major flaws that have been discovered in software used in industrial networks. Earlier this June, Claroty detailed over a dozen issues in Siemens SINEC network management system (NMS) that could be abused to gain remote code execution capabilities.
Then in April 2022, the company unwrapped two vulnerabilities in Rockwell Automation PLCs (CVE-2022-1159 and CVE-2022-1161) that could be exploited to modify user programs and download malicious code to the controller.
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