Cybersecurity Threat Spotlight: Emotet, RedLine Stealer, and Magnat Backdoor

Security and IT teams may be fresh off their holiday breaks, but threat actors have kept busy over the last month. In this edition of the Cybersecurity Threat Spotlight, we’re highlighting the Trojans, loaders, information stealers, and backdoors that we’re seeing online.

Want to learn more about how Cisco Umbrella can defend your enterprise against these threats? Request a personalized demo today!


Threat Name: Emotet

Threat Type: Trojan/Loader

Attack Chain:

A graphic showing the attack chain for Emotet: Malspam to Weaponized Document/Archive to Malicious Macros to Emotet Loader to CobaltStrike to Conti Ransomware. The graphic indicates that Cisco Umbrella protects users against Weaponized Document/Archive, Emotet Loader, and Cobalt Strike.

Description: Emotet is a banking Trojan that was first detected in 2014. Emotet has evolved into a massive botnet that delivers large amounts of malspam with malicious document attachments that lead to the Emotet Trojan. The Trojan also functions as a dropper for second-stage payloads, including – but not limited to – TrickBot, Qakbot, and Ryuk. Emotet has can steal SMTP credentials and email content. The threat actors reply to legitimate conversations in a victim’s email account, injecting replies that include malicious attachments.

Emotet Spotlight: In November, security researchers observed the return of the Emotet loader, which had been inactive since January 2021 after a law enforcement takedown. Emotet is a loader botnet that uses a Loader-as-a-Service model. Emotet’s main advantage is its modular system, which enables a highly targeted approach based on the requirements of the delivered payload. Unfortunately, the botnet has historically been leveraged by adversaries conducting sophisticated ransomware attacks.

At this point, security researchers observe strong connections between Emotet and Conti Ransomware. This can indicate that two cybercriminal syndicates are or will be establishing a new partnership. Historically, Conti was known to rely on sustainable methods of operation. Emotet has proven to be able to provide initial access and a strong foothold in multiple corporate networks. This can become the new trend in adversaries, and it will likely have a major impact on the threat landscape in 2022.

Target Geolocations: Worldwide
Target Data: User Credentials, Browser Data, Sensitive Information
Target Businesses: Any
Exploits: N/A

Mitre ATT&CK for Emotet

Initial Access:
Phishing: Spearphishing Attachment or Spearphishing Link, Valid Accounts: Local Accounts
Discovery:
Account Discovery
Process Discovery
Persistence:
Boot or Logon Autostart Execution: Registry Run Keys/Startup Folder
Create or Modify System Process: Windows Service
Scheduled Task/Job: Scheduled Task
Execution:
Command and Scripting Interpreter: PowerShell, Windows Command Shell, Visual Basic
User Execution: Malicious Link, Malicious File
Windows Management Instrumentation
Evasion:
Obfuscated Files or Information
Software Packing
Collection:
Archive Collected Data
Email Collection: Local Email Collection
Credential Access:
Brute Force: Password Guessing
Credentials From Password Stores: Credentials from Web Browsers
Network Sniffing
OS Credential Dumping: LSASS Memory
Unsecured Credentials: Credentials In Files
Command and Control:
Encrypted Channel: Asymmetric Cryptography, Non-Standard Port
Exfiltration:
Exfiltration Over C2 Channel
Lateral Movement:
Exploitation of Remote Services
Remote Services: SMB/Windows Admin Shares
Privilege Escalation:
Process Injection: Dynamic-Link Library Injection

IOCs:

Domains (Active)

cars-taxonomy[.]mywebartist[.]eu
crownadvertising[.]ca
giadinhviet[.]com
hpoglobalconsulting[.]com
immoinvest[.]com[.]br
itomsystem[.]in
pasionportufuturo[.]pe
thetrendskill[.]com
visteme[.]mx
cursossemana[.]com
callswayroofco[.]com
dipingwang[.]com
yougandan[.]com

Domains (Historical)

adorwelding[.]zmotpro[.]com
alfadandoinc[.]com
alfaofarms[.]com
av-quiz[.]tk
ceshidizhi[.]xyz
ckfoods[.]netdevanture[.]com[.]sg
evgeniys[.]ru
goodtech[.]cetxlabs[.]com
html[.]gugame[.]net
huskysb[.]com
im2020[.]vip
jamaateislami[.]com
laptopinpakistan[.]com
linebot[.]gugame[.]net
lpj917[.]com
manak[.]edunetfoundation[.]org
newsmag[.]danielolayinkas[.]com
onlinemanager[.]site
parentingkiss[.]com
pibita[.]net
primtalent[.]com
protracologistics[.]com
ranvipclub[.]net
ridcyf[.]com
server[.]zmotpro[.]com
staviancjs[.]com
team[.]stagingapps[.]xyz
thepilatesstudionj[.]com
vcilimitado[.]com
vegandietary[.]com
voltaicplasma[.]com
www[.]168801[.]xyz
www[.]caboturnup[.]com
xanthelasmaremoval[.]com
yoho[.]love

IPs (Active)

151[.]80[.]142[.]33
87 [.] 248 [.] 77 [.] 159
159 [.] 65 [.] 76 [.] 245

IPs (Historical)

105[.]247[.]100[.]215
118[.]244[.]214[.]210
120[.]150[.]206[.]156
12[.]57[.]239[.]19
139[.]162[.]157[.]8
139[.]59[.]242[.]76
169[.]64[.]242[.]153
173[.]90[.]152[.]220
179[.]52[.]236[.]96
181[.]119[.]30[.]35
181[.]229[.]155[.]11
185[.]129[.]3[.]211
185[.]97[.]32[.]6
186[.]176[.]182[.]192
186[.]4[.]234[.]27
189[.]130[.]50[.]85
189[.]234[.]165[.]149
190[.]128[.]27[.]233
200[.]27[.]55[.]100
200[.]56[.]104[.]44
208[.]180[.]149[.]228
208[.]180[.]246[.]147
216[.]176[.]21[.]143
216[.]251[.]1[.]1
23[.]254[.]203[.]51
24[.]206[.]17[.]102
37[.]120[.]175[.]15
45[.]123[.]3[.]54
50[.]100[.]215[.]149
50[.]125[.]99[.]70
51[.]75[.]168[.]89
54[.]39[.]176[.]22
54[.]39[.]181[.]130
67[.]215[.]49[.]234
67[.]43[.]253[.]189
86[.]98[.]71[.]86
92[.]207[.]145[.]74
96[.]246[.]206[.]16

Additional Information:

Back from the dead: Emotet re-emerges, begins rebuilding to wrap up 2021
Corporate Loader “Emotet”: History of “X” Project Return for Ransomware

Which Cisco Products Can Block:

Cisco Secure Endpoint
Cisco Secure Email
Cisco Secure Firewall/Secure IPS
Cisco Secure Malware Analytics
Cisco Umbrella
Cisco Secure Web Appliance


Threat Name: RedLine Stealer

Threat Type: Information Stealer

Attack Chain:

A graphic showing the attack chain for RedLine Stealer: Malspam Link/Trojanized App Download to RedLine Malware to Information Stealing to Command and Control. The graphic indicates that Cisco Umbrella protects against Malspam Link/Trojanized App Download, RedLine Malware, and Command and Control.

Description: RedLine is an information stealer available as a Malware-as-a-Service (MaaS) on Russian underground forums. It steals information like login credentials, autocomplete fields, passwords, and credit card information from browsers. It also collects information about the user and their system, like the username, location, hardware configuration, and installed security software. Finally, a recent update to RedLine also adds the ability to stead cryptocurrency cold wallets. RedLine appears to be under active development, with frequent introductions of new features.

RedLine Spotlight: Security researchers discovered that most stolen credentials currently sold on the dark web underground markets had been collected using RedLine Stealer malware. RedLine Stealer attempts to harvest information from browsers – like passwords, cryptocurrency wallets, and VPN services – and system information – like hardware configuration and location. Over the past year, RedLine has been enhanced with the addition of new features. It is now capable of loading other malware software and running commands while periodically sending updates containing new information from the infected host to its C2. The main goal of cybercrime campaigns utilizing RedLine Stealer appears to be the sale of stolen data to other cybercriminals who weaponize it in their own attacks.

Target Geolocations: Any
Target Data: User Credentials, Browser Data, Financial and Personal Information, Cryptocurrency Wallets
Target Businesses: Any
Exploits: N/A

MITRE ATT&CK for RedLine

Initial Access:
Phishing
Trojanized Applications
Credential Access:
Credentials from Password Stores
Steal Web Session Cookie
Unsecured Credentials
Credentials from Password Stores: Credentials from Web Browsers
Discovery:
Account Discovery
Software Discovery
Process Discovery
System Time Discovery
System Service Discovery
System Location Discovery
Peripheral Device Discovery
Persistence:
Registry Run Keys/Startup Folder
Scheduled Task/Job: Scheduled Task
Execution:
User Execution
Command and Scripting Interpreter: PowerShell
Evasion:
Impair Defenses: Disable or Modify Tools
Collection:
Screen Capture
Command and Control:
Non-Standard Port
Non-Application Layer Protocol
Exfiltration:
Exfiltration Over C2 Channel

IOCs

Domains (Historical)

userauto[.]space
22231jssdszs[.]fun
hssubnsx[.]xyz
dshdh377dsj[.]fun

IPs (Active)

185[.]215[.]113[.]114

IPs (Historical)

37[.]0[.]8[.]88
193[].142[.]59[.]119
136[.]144[.]41[.]201

Additional Information

RedLine Stealer identified as primary source of stolen credentials on two dark web markets
Redline Stealer
Shining a Light on RedLine Stealer Malware and Identity Data Found in Criminal Shops

Which Cisco Products Can Block:
Cisco Secure Endpoint
Cisco Secure Email
Cisco Secure Firewall/Secure IPS
Cisco Secure Malware Analytics
Cisco Umbrella
Cisco Secure Web Appliance


Threat Name: Magnat Backdoor

Threat Type: BackDoor

Attack Chain:[1]

Graphic showing the attack chain for Magnat BackDoor: Malvertising to Download Fake Installer to Dee-Obfuscation to RDP Backdoor/Information Stealer/Chrome Extension Installer to Command and Control. The graphic indicates that Umbrella protects users against Malvertising, Download Fake Installer, RDP Backdoor/Information Stealer, and Command and Control

Description: Magnat BackDoor is an AutoIt-based installer that prepares a system for remote Microsoft Desktop Access and forwards the RDP service port on an outbound SSH tunnel. This installer’s actions pave the way for the attacker to access the system remotely via RDP. The malware applies this technique by setting up a scheduled task that periodically contacts a C2 server and sets up the tunnel if instructed by the C2 response.

Magnat BackDoor Spotlight: Cisco Talos recently observed a malicious campaign offering fake installers of popular software as bait to get users to execute the malware on their systems. This campaign includes a set of malware distribution campaigns that started in late 2018 and have targeted Canada, the U.S., Australia, and some European Union countries. Two undocumented malware families (a BackDoor and a Google Chrome extension) are consistently delivered together in these campaigns. An unknown actor with the alias “magnat” is likely the author of these new families and has consistently developed and improved them. The attacker’s motivations appear to be financial gain from selling stolen credentials, executing fraudulent transactions, and providing Remote Desktop Access to systems.

Target Geolocations: Canada, U.S., Australia, E.U. Countries
Target Data: Credentials, Sensitive Data
Target Businesses: Any

MITRE ATT&ACK for Magnat BackDoor

Initial Access:
Malvertising
Persistence:
Scheduled Task/Job
Execution:
Scheduled Task/Job
Evasion:
Impair Defenses: Disable or Modify System Firewall
Deobfuscate/Decode Files or Information
Command and Control:
Application Layer Protocol
Exfiltration:
Exfiltration Over Command and Control Channel

IOCs

Domains (Active)

chocolatepuma[.]casa
wormbrainteam[.]club
430lodsfb[.]xyz
softstatistic[.]xyz
happyheadshot[.]club
aaabasick[.]fun
nnyearhappy[.]club
teambrainworm[.]club
yanevinovat[.]club
fartoviypapamojetvse[.]club
hugecarspro[.]space
burstyourbubble[.]icu
boogieboom[.]host
cgi-lineup[.]website
newdawnera[.]fun
bhajhhsy6[.]site
iisnbnd7723hj[.]digital
sdcdsujnd555w[.]digital

Additional Information:

Magnat campaigns use malvertising to deliver information stealer, backdoor and malicious Chrome extension

Which Cisco Products Can Block:
Cisco Secure Endpoint
Cisco Secure Firewall/Secure IPS
Cisco Secure Malware Analytics
Cisco Umbrella


[1] While Cisco products can protect against RDP BackDoor and Information Stealer, they do not protect against Chrome Extension Installers

Source :
https://umbrella.cisco.com/blog/cybersecurity-threat-spotlight-emotet-redline-stealer-magnat-backdoor

Why You Need to Care About Data Privacy & 5 Tips for Better Data Security

The privacy of our data has always been important. However, because we’re sharing more of it than ever before, being aware of data privacy and taking the necessary steps to protect it has never been more crucial. In this article, in celebration of Data Privacy Week, we cover why data privacy is so important, what can happen if your data were to fall into the wrong hands, and what you can do to protect your personal data.

Find out if your email address appeared in any data leaks

What is data privacy and why is it important?

Data privacy often refers to the practice of handling sensitive data in line with regulatory requirements. In most developed countries, there are specific data privacy laws in place that regulate how companies can collect, store, and share customer data.

While the EU has a comprehensive data privacy law, the General Data Protection Regulation (GDPR), which covers all different types of data, only three US states currently have similar, all-encompassing data privacy laws (California, Virginia, and Colorado). Instead, the US has many different laws designed to target specific types of data. For example, the Fair Credit Reporting Act (FCRA) protects information in your credit report, and the Family Educational Rights and Privacy Act (FERPA) protects students’ education reports from being freely accessible.

However, because of how much time we spend online nowadays, we’re putting more of our personal data out there for others to see than ever before. As a result, it is not only important to understand how protected your data is when you share it with a company, but also how private it is when you share it online.

How to protect your data privacy

Here are some of our top tips for data privacy protection:

  1. Only give your data to trustworthy companies and websites — Perhaps you’ve come across a new online clothing store or seen an app on the app store that takes your fancy, but you’re unsure if you can trust the company. If you’ve never heard of the company before, it’s best to do some quick research to learn whether or not you can trust it with your data.
  2. Think twice before sharing — With social media being such a big part of our everyday lives, it’s easy to forget that what we post online, stays online forever. Always think twice before sharing something online. Don’t publicly share personal information such as your address, phone number, or social security number.
  3. Take advantage of privacy settings — On every website, app, and game that you use, make sure you’re taking advantage of the built-in privacy settings. By doing so, you’ll ensure that only people you know can view your information.
  4. Use strong passwords and enable 2FA — When you create an online account, you almost always need to share lots of personal data — your full name, email address, and date of birth, for example. Although this data isn’t publicly accessible, if a hacker were to gain access to one of your accounts, they would be able to see all this information. To avoid this happening, make sure to use only strong, tough-to-hack passwords and that all your accounts have two-factor authentication (2FA) enabled.
  5. Use a VPN on public Wi-Fi — Unprotected Wi-Fi networks are notoriously unsecure. Because no password is required to access them, nearby hackers can steal any data transferred over them. To protect yourself, always use a VPN on public Wi-Fi networks.

Data leaks in 2021 — T-Mobile, LinkedIn, Moncler & CoinMarketCap

The truth is, no matter how well a company abides by data privacy laws and how thoroughly it protects its customers’ data, it can never be 100% data leak-proof. In 2021 alone, a shocking number of companies suffered high-profile data leaks, including T-MobileLinkedInMoncler, and CoinMarketCap. Those leaks resulted in hundreds of millions of people having their sensitive personal data leaked, which is used by criminals to commit all sorts of crimes — with the most concerning of them all being identity theft.

According to the Federal Trade Commission, there were over 1 million reports of identity theft in 2021. Below are some of the things the FTC says criminals can do with your data:

  • Get new credit cards in your name.
  • Open a phone, electricity, or gas account in your name.
  • Steal your tax refund.
  • Get medical care under your name (and leave you with a huge bill!).
  • Pretend to be you if they get arrested.

Cybercriminals often put stolen data up for sale on underground forums on the regular internet, as well as the dark web. And as you can imagine, personal information that is particularly valuable to them can fetch a high price. On average, on the dark web, a driver’s license will go for $205, an ID card for $213, and a passport sells for a whopping $684!

How to stay protected from data leaks

You might be thinking that staying protected from data leaks is an impossible task, but the answer is easy: Trend Micro™ ID Security . Available for Android and iOS, Trend Micro™ ID Security can scan the internet and the dark web 24/7 for your personal information. If your data is leaked, the app notifies you immediately so you can take action to avoid people stealing your identity. If your information is out there, you’ll be the first to know!

Here are some of the features offered by Trend Micro™ ID Security :

  • Personal Data Protection Score — See exactly how safe your online personal data is with your customized Protection Score.
  • 24/7 Comprehensive Personal Data Monitoring — ID Security can scan the internet and the dark web for all your personal information including up to 5 email addresses and bank account numbers, 10 credit card numbers, your Social Security number, and lots more.
  • Social Media Account Protection — Strengthen the security of your social media accounts. Be instantly alerted if your Facebook or Twitter account’s data is leaked by cybercriminals.

To learn more about Trend Micro™ ID Security and claim your free 30-day trial, click the button below.Get ID Security

Source :
https://news.trendmicro.com/2022/01/27/why-you-need-to-care-about-data-privacy-5-tips-for-better-data-security/

How to Detect Malware on iPhone — 5 Steps

Have you noticed your iPhone behaving a little strangely recently? Maybe you’ve been bombarded by unusual ads or your battery has been hitting 0% much more quickly than normal. If you’ve got your suspicions that your iPhone has a malware infection, keep on reading to learn how to know for sure!

Step #1 — Check for high data usage

One particularly big sign of a malware infection is if your iPhone is using much more data than normal. Follow the instructions below to check:

  1. Go to either Settings > Cellular or Settings > Mobile Data (depending on which version of iOS you have, it will be different).
  2. You will then be able to check exactly how much data you’ve used in the current period. If it is significantly higher than you’re used to, search through the list of apps and look for any that you don’t recognize or remember installing. If any of them are using up a lot of data, you should strongly consider deleting them because they could be malicious.

Step #2 — Check for battery-hogging apps 

Some forms of malware can run in the background without you even being aware of it, consuming huge amounts of your iPhone’s resources and having a significant impact on how long its battery lasts. As a result, similar to an increase in data usage, a sudden increase in battery usage is another red flag that indicates that your iPhone may have a problem. Here’s how you can check:

  1. Navigate to Settings and select Battery.
  2. Choose either Last 24 hours or Last 10 Days.
  3. You can now see every app’s battery usage during the selected time period. Just like checking for high data usage, if you see any unusual apps that are using up a lot of battery, you should delete them.

Step #3 — Check for strange apps

Malware comes in many different varieties. While it is true that many consume a lot of battery and data, it is not the case for all malicious apps. Because of this, you also need to simply scan through every app installed on your iPhone and look for ones you don’t recognize.

This step may take a while, especially if you’ve installed lots of them, but scan through all your apps and search for ones that you don’t recognize. Every time you see an unfamiliar one, you should remove it.

Step #4 — Constantly being bothered by pop-ups?

If you’re always being bombarded by ads every time you surf the web on your iPhone, it’s a very strong sign that it has been infected by adware, which is a particular form of malware. Although it is generally considered one of the less dangerous types of malware, it can still be very annoying. If you’re suffering from this issue, but you were unable to find any malicious apps while following the previous steps, you should move on to the next step.

Step #5 — Run a malware scan

If you were unsuccessful in detecting any malware-infected apps while following the instructions in the previous steps and your iPhone is still behaving unusually, you need to run a malware scan — Trend Micro Mobile Security  works perfectly for this!

Trend Micro Mobile Security can protect you against malicious apps, ransomware, dangerous websites, unsafe Wi-Fi networks, and more. Ridding your iPhone of malware simply couldn’t be any easier! Click the button below to download.Get Mobile Security

Some of Trend Micro Mobile Security ’s awesome features include:

  • Surf anywhere —Prevent mobile apps from loading dangerous and risky websites when you browse.
  • Stop threats —Rely on the cloud-based Smart Protection Network™ and Mobile App Reputation technology to stop threats before they can reach you.
  • Avoid online scams and fraud —Flag malicious phishing emails and scam websites.
  • Improve performance — Take advantage of optimization features to make your mobile devices work better.

    Source :
    https://news.trendmicro.com/2022/01/26/how-to-detect-malware-on-iphone-5-steps/

Raspberry Pi OS (64-bit)

Over the past year, we’ve been trialling a beta of Raspberry Pi OS in glorious 64-bit. Now it’s time to open it up to a wider audience.

raspberry pi os 64-bit

The ARMv8-A architecture, which encompasses the 64-bit AArch64 architecture and associated A64 instruction set, was first introduced into the Raspberry Pi line with Raspberry Pi 3 in 2016. From that point on, it has been possible to run a full 64-bit operating system on our flagship products, and many third-party operating systems are available. However, we have continued to build our Raspberry Pi OS releases on the 32-bit Raspbian platform, aiming to maximise compatibility between devices and to avoid customer confusion.

ProductProcessorARM coreDebian/Raspbian ARM
port (maximum)
Architecture
width
Raspberry Pi 1BCM2835ARM1176arm6hf32 bit
Raspberry Pi 2BCM2836Cortex-A7armhf32 bit
Raspberry Pi ZeroBCM2835ARM1176arm6hf32 bit
Raspberry Pi Zero 2BCM2710Cortex-A53arm6464 bit
Raspberry Pi 3BCM2710Cortex-A53arm6464 bit
Raspberry Pi 4BCM2711Cortex-A72arm6464 bit

As you can see from the table above, it is easy to be confused about which products will support which Debian/Raspbian ports. Using arm6hf (Raspbian’s derivative of armhf with ARMv7-only instructions removed but floating-point instructions retained) provides us with an operating system which will run on every device we have ever manufactured, all the way back to 2011.

But we’ve come to realise that there are reasons to choose a 64-bit operating system over a 32-bit one. Compatibility is a key concern: many closed-source applications are only available for arm64, and open-source ones aren’t fully optimised for the armhf port. Beyond that there are some performance benefits intrinsic to the A64 instruction set: today, these are most visible in benchmarks, but the assumption is that these will feed through into real-world application performance in the future.

A more theoretical concern is that 32-bit pointers only allow you to address 4GB of memory. On Raspberry Pi 4, we use the ARM Large Physical Address Extension (LPAE) to access up to 8GB of memory, subject to the constraint that any process is limited to accessing 3GB (we reserve the top 1GB of the virtual address space for the kernel). Very few processes require more memory than this: happily Chromium, which is probably the most memory-intensive application in Raspberry Pi OS, spawns a process per tab. But some use cases will benefit from being able to allocate the entire memory of an 8GB Raspberry Pi 4 from a single process.

The 64-bit version of Chromium, installed by default, has no version of the WidevineCDM library and therefore, it is not possible to play streaming media such as Netflix or Disney+.  To instead choose the 32-bit version just do the following within a terminal window:

sudo apt install chromium-browser:armhf libwidevinecdm0

To return to the 64-bit version

sudo apt install chromium-browser:arm64 libwidevinecdm0-

So, head to the downloads page and grab your copy of 64-bit Raspberry Pi OS today. Let us know in the comments if your use case benefits (or suffers!) from the move to 64-bit.

Source :
https://www.raspberrypi.com/news/raspberry-pi-os-64-bit/

Microsoft Office 365 boosts email security against MITM, downgrade attacks

Microsoft has added SMTP MTA Strict Transport Security (MTA-STS) support to Exchange Online to ensure Office 365 customers’ email communication integrity and security.

Redmond first announced MTA-STS’ introduction in September 2020, after revealing that it was also working on adding inbound and outbound support for DNSSEC (Domain Name System Security Extensions) and DANE for SMTP (DNS-based Authentication of Named Entities).

“We have been validating our implementation and are now pleased to announce support for MTA-STS for all outgoing messages from Exchange Online,” the Exchange Online Transport Team said today.

With MTA-STS now available in Office 365, emails sent by users via Exchange Online will only be delivered using connections with both authentication and encryption, protecting the messages from interception and attack attempts.

This new standard strengthens Exchange Online email security and solves several SMTP security problems, including expired TLS certificates, the lack of support for secure protocols, and certificates not issued by trusted third parties or matching server domain names.

Before MTA-STS, emails sent through improperly secured TLS connections were exposed to various attacks, including downgrade and man-in-the-middle attacks.

“Downgrade attacks are possible where the STARTTLS response can be deleted, thus rendering the message in cleartext. Man-in-the-middle (MITM) attacks are also possible, whereby the message can be rerouted to an attacker’s server,” the Exchange team said.

“MTA-STS (RFC8461) helps thwart such attacks by providing a mechanism for setting domain policies that specify whether the receiving domain supports TLS and what to do when TLS can’t be negotiated, for example stop the transmission.”

Microsoft provides guidance on how to adopt MTA-STS, including where to host the policy file on your domain’s web infrastructure.https://www.youtube.com/embed/VY3YvrrHXJk

DANE for SMTP support also rolling out

Redmond is still working on rolling out DANE for SMTP (with DNSSEC support), which provides better protection for SMTP connections than MTA-STS does.

“We will deploy support for DANE for SMTP and DNSSEC in two phases. The first phase, DANE and DNSSEC for outbound email (from Exchange Online to external destinations), is slowly being deployed between now and March 2022. We expect the second phase, support for inbound email, to start by the end of 2022,” said The Exchange Team on Tuesday.

“We’ve been working on support for both MTA-STS and DANE for SMTP. At the very least, we encourage customers to secure their domains with MTA-STS,” Microsoft added today.

“You can use both standards on the same domain at the same time, so customers are free to use both when Exchange Online offers inbound protection using DANE for SMTP by the end of 2022. By supporting both standards, you can account for senders who may support only one method.”

Microsoft has already secured several domains it uses for email transport as a domain owner itself, including primary domains like outlook.com, hotmail.com, and live.com. 

This ensures that all connections from senders who support MTA-STS are better protected from man-in-the-middle attacks. 

Source :
https://www.bleepingcomputer.com/news/microsoft/office-365-boosts-email-security-against-mitm-downgrade-attacks/

Microsoft Windows 10 optional updates fix performance problems introduced last month

Optional updates for Windows 10 and Windows 11 released in January have fixed performance problems when playing games, using the operating system, or even opening folders in File Explorer.

With the January 2022 updates, Microsoft introduced numerous bugs breaking LT2P VPN connections, causing domain controller reboots, and preventing Hyper-V from working.

Microsoft later released out-of-band updates to fix these issues, whose fixes were also rolled into the optional preview updates.

However, these optional updates seem to have fixed more than the reported bugs, as they are also resolving significant performance issues caused by the January updates.

Recent Windows updates caused performance hits

After installing the January 2022 KB5009543 update, Windows 10 users began to notice that Windows suffered from severe performance issues.

These performance issues included slow boots and slow response times when opening the Start Menu, launching apps, playing games, and performing pretty much all of the basic functions of the operating system. In general, Windows felt “laggy” after installing the updates.

“Prior to the update, it took maybe 2 minutes for my laptop to boot to the home screen. It now takes close to a half hour. I’m frustrated to the point where I’m now planning to disable updates and uninstall this update,” a user named Ninja_Bobcat posted on Reddit.

“This update has ruined my laptop in games, namely warzone and apex. Goes to 0 fps and huge stutters everywhere,” another person posted.

“My computer is incredibly slow after KB5009543 security update and KB5008876 windows update. It takes about 3 minutes for my computer to boot and maybe 2-3 minutes to open a tab on chrome. Absolutely killed my computer,” said a third Windows 10 user.

BleepingComputer replicated these performance issues after installing the January 2022 KB5009543 update on multiple laptops.

The good news is that BleepingComputer found that installing the optional KB5009596 preview update released late last month fixed these newly introduced performance issues.

Windows 10 KB5009596 optional update
Windows 10 KB5009596 optional update

However, as these updates are optional, many users will not know to install them. Thus, their performance issues will continue until the mandatory February 2022 Patch Tuesday updates are installed, which will include these fixes.

Windows users can install the optional updates by going into Settings, clicking on Windows Update, and manually performing a ‘Check for Updates.’

As this is an optional update, you will need to install the KB5009596 by clicking on the ‘Download and install’ link.

Windows 11 issues were fixed as well

Not to be outdone by Windows 10, Windows 11 has also been dealing with performance issues within File Explorer.

Users found that it was slow to switch between folders, browse folders, or select files when using File Explorer.

However, the optional Windows 11 KB5008353 cumulative update preview has resolved these issues, with users reporting that File Explorer is back to normal.

“I honestly lost hope because this issue has been there since I upgraded to Win11, other users were claiming it was solved but it wasn’t the case for everyone. However, this update seems to have fixed this issue for good amongst others of course,” a Windows 11 user posted on Reddit.

BleepingComputer has not been able to replicate the performance issues on Windows 11 to test the fix.

BleepingComputer has also reached out to Microsoft with further questions about what has been fixed but has not received a reply as of yet.

Source :
https://www.bleepingcomputer.com/news/microsoft/windows-10-optional-updates-fix-performance-problems-introduced-last-month/

A physical disk resource may not come online on a Microsoft cluster node

This article helps solve an issue where a physical disk resource doesn’t come online on a cluster node.

Applies to:   Windows Server 2012 R2
Original KB number:   981475

Symptoms

On a cluster node that is running Windows Server, a physical disk resource may enter the Failed state when you try to move a group that contains the physical disk resource. If you restart the cluster node that has the physical disk resource that did not come online, the problem is temporarily resolved.

When this problem occurs, the following entries are logged in the Cluster log for the physical disk resource that entered the failed state:

000020cc.000014d0::<DateTime> ERR Physical Disk <Disk Q:>:
DiskspCheckPath: GetFileAttrs(Q:) returned status of 87.
000020cc.000014d0::<DateTime> WARN Physical Disk <Disk Q:>:
DiskspCheckDriveLetter: Checking drive name (Q:) returns 87

Additionally, the following events are logged in the System Event log:

Event Type: Error
Event Source: ClusSvc
Event Category: Physical Disk Resource
Event ID: 1066
Date: <date>
Time: <time>
User: N/A
Computer: <node name>
Description: Cluster disk resource “Disk Q:” is corrupt. Run ‘ChkDsk /F’ to repair problems. The volume name for this resource is “<\?\Volume{4323d41e-1379-11dd-9538-001e0b20dfe6}>”. If available, ChkDsk output will be in the file “C:\WINDOWS\Cluster\ChkDsk_Disk2_SigB05E593B.log”. ChkDsk may write information to the Application Event Log with Event ID 26180.

Event Type: Error
Event Source: ClusSvc
Event Category: Physical Disk Resource
Event ID: 1035
Date: <date>
Time: <time>
User: N/A
Computer: <node name>
Description: Cluster disk resource ‘Disk Q:’ could not be mounted.

Similarly, on a Windows Server cluster node you may see following entries are logged in the Cluster log:

00000db0.00000868::<DateTime> WARN [RES] Physical Disk <Cluster Disk 1>: OnlineThread: Failed to get volume guid for device \?\GLOBALROOT\Device\Harddisk15\Partition1. Error 3
00000db0.00000868::<DateTime> WARN [RES] Physical Disk <Cluster Disk 1>: OnlineThread: Failed to set volguid ??\Volume{3cb36133-0d0b-11df-afcf-005056ab58b9}. Error: 183.
00000db0.00000868::<DateTime> INFO [RES] Physical Disk <Cluster Disk 1>: VolumeIsNtfs: Volume \?\GLOBALROOT\Device\Harddisk15\Partition1\ has FS type NTFS

Cause

This problem is known to occur when antivirus software that is not cluster-aware is installed, upgraded, or reconfigured. For example, this problem is known to occur after you install or migrate to Symantec Endpoint Protection 11.0 Release Update 5 (RU5) on the cluster nodes.

Resolution

To resolve this problem, follow these steps:

  1. Verify that this problem is caused by Symantec Endpoint Protection (SEP) 11.0 Release Update 5 (RU5). To do this, run the Handle.exe utility immediately after the issue occurs on the cluster node where the physical disk resource did not come online.At an elevated command prompt, type the following command, and then press ENTER: Handle.exe -a -u drive_letter. NoteThe drive_letter placeholder is the drive designation for the cluster drive that did not come online.For example, assume that the drive designation for the cluster drive that did not come online is drive Q. To run the Handle.exe utility in this scenario, type the following command, and then press ENTER: Handle.exe -a -u Q:.The problem is caused by the Symantec application if you receive the following message that identifies the Smc.exe process as the process that owns the handle:Handle v3.42
    Copyright (C) 1997-2008 Mark Russinovich
    Sysinternals – www.sysinternals.comSmc.exe pid: 856 NT AUTHORITY\SYSTEM 66C: Q:
  2. If the problem is caused by the Symantec application, contact Symantec to obtain Symantec Endpoint Protection 11 Release Update 6 (RU6), which was released to resolve this issue.

More information

For more information about the Handle.exe utility, see Handle v4.22.

The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, about the performance or reliability of these products.

Source :
https://docs.microsoft.com/en-us/troubleshoot/windows-server/high-availability/physical-disk-resource-not-come-online

Microsoft Cluster Shared Volume (CSV) Inside Out

In this blog we will take a look under the hood of the cluster file system in Windows Server 2012 R2 called Cluster Shared Volumes (CSV). This blog post is targeted at developers and ISV’s who are looking to integrate their storage solutions with CSV.

Note: Throughout this blog, I will refer to C:\ClusterStorage assuming that the Windows is installed on the C:\ drive. Windows can be installed on any available drive and the CSV namespace will be built on the system drive, but instead of using %SystemDrive%\ClusterStorage\ I’ve used C:\ClusteredStorage for better readability since C:\ is used as the system drive most of the time.

Components


Cluster Shared Volume in Windows Server 2012 is a completely re-architected solution from Cluster Shared Volumes you knew in Windows Server 2008 R2. Although it may look similar in the user experience – just a bunch of volumes mapped under the C:\ClusterStorage\ and you are using regular windows file system interface to work with the files on these volumes, under the hood, these are two completely different architectures. One of the main goals is that in Windows Server 2012, CSV has been expanded beyond the Hyper-V workload, for example Scale-out File Server and in Windows Server 2012 R2 CSV is also supported with SQL Server 2014.

First, let us look under the hood of CsvFs at the components that constitute the solution.


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Cluster Shared Volume (CSV) Inside Out

Figure 1:

CSV Components and Data Flow Diagram



The diagram above shows a 3 node cluster. There is one shared disk that is visible to Node 1 and Node 2. Node 3 in this diagram has no direct connectivity to the storage. The disk was first clustered and then added to the Cluster Shared Volume. From the user’s perspective, everything will look the same as in the Windows 2008 R2. On every cluster node you will find a mount point to the volume: C:\ClusterStorage\Volume1. The “VolumeX” naming can be changed, just use Windows Explorer and rename like you would any other directory.  CSV will then take care of synchronizing the updated name around the cluster to ensure all nodes are consistent.  Now let’s look at the components that are backing up these mount points.

Terminology

The node where NTFS for the clustered CSV disk is mounted is called the Coordinator Node. In this context, any other node that does not have clustered disk mounted is called Data Servers (DS). Note that coordinator node is always a data server node at the same time. In other words, coordinator is a special data server node when NTFS is mounted.

If you have multiple disks in CSV, you can place them on different cluster nodes. The node that hosts a disk will be a Coordinator Node only for the volumes that are located on that disk. Since each node might be hosting a disk, each of them might be a Coordinator Node, but for different disks. So technically, to avoid ambiguity, we should always qualify “Coordinator Node” with the volume name. For instance we should say: “Node 2 is a Coordinator Node for the Volume1”. Most of the examples we will go through in this blog post for simplicity will have only one CSV disk in the cluster so we will drop the qualification part and will just say Coordinator Node to refer to the node that has this disk online.

Sometimes we will use terms “disk” and “volume” interchangeably because in the samples we will be going through one disk will have only one NTFS volume, which is the most common deployment configuration. In practice, you can create multiple volumes on a disk and CSV fully supports that as well. When you move a disk ownership from one cluster node to another, all the volumes will travel along with the disk and any given node will be the coordinator for all volumes on a given disk. Storage Spaces would be one exception from that model, but we will ignore that possibility for now.


This diagram is complicated so let’s try to break it up to the pieces, and discuss each peace separately, and then hopefully the whole picture together will make more sense.

On the Node 2, you can see following stack that represents mounted NTFS. Cluster guarantees that only one node has NTFS in the state where it can write to the disk, this is important because NTFS is not a clustered file system.  CSV provides a layer of orchestration that enables NTFS or ReFS (with Windows Server 2012 R2) to be accessed concurrently by multiple servers. Following blog post explains how cluster leverages SCSI-3 Persistent Reservation commands with disks to implement that guarantee https://techcommunity.microsoft.com/t5/Failover-Clustering/Cluster-Shared-Volumes-CSV-Disk-Ownership….



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Cluster Shared Volume (CSV) Inside Out

Figure 2:

CSV NTFS stack



Cluster makes this volume hidden so that Volume Manager (Volume in the diagram above) does not assign a volume GUID to this volume and there will be no drive letter assigned. You also would not see this volume using mountvol.exe or using FindFirstVolume() and FindNextVolume() WIN32 APIs.

On the NTFS stack the cluster will attach an instance of a file system mini-filter driver called CsvFlt.sys at the altitude 404800. You can see that filter attached to the NTFS volume used by CSV if you run following command:

>fltmc.exe instances


Filter       Volume Name                      Altitude   Instance Name

———  —————————      ———  ———————-

<skip>
CsvFlt     \Device\HarddiskVolume7   404800     CsvFlt Instance

<skip>


Applications are not expected to access the NTFS stack and we even go an extra mile to block access to this volume from the user mode applications. CsvFlt will check all create requests coming from the user mode against the security descriptor that is kept in the cluster public property SharedVolumeSecurityDescriptor. You can use power shell cmdlet “Get-Cluster | fl SharedVolumeSecurityDescriptor” to get to that property. The output of this PowerShell cmdlet shows value of the security descriptor in self-relative binary format ( http://msdn.microsoft.com/en-us/library/windows/desktop/aa374807(v=vs.85).aspx 🙁
PS > Get-Cluster | fl SharedVolumeSecurityDescriptorSharedVolumeSecurityDescriptor : {1, 0, 4, 128…}


CsvFlt plays several roles:

  • Provides an extra level of protection for the hidden NTFS volume used for CSV
  • Helps provide a local volume experience (after all CsvFs does look like a local volume). For instance you cannot open volume over SMB or read USN journal. To enable these kinds of scenarios CsvFs often times marshals the operation that need to be performed to the CsvFlt disguising it behind a tunneling file system control. CsvFlt is responsible for converting the tunneled information back to the original request before forwarding it down-the stack to NTFS.
  • It implements several mechanisms to help coordinate certain states across multiple nodes. We will touch on them in the future posts. File Revision Number is one of them for example.

The next stack we will look at is the system volume stack. On the diagram above you see this stack only on the coordinator node which has NTFS mounted. In practice exactly the same stack exists on all nodes.



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Cluster Shared Volume (CSV) Inside Out

Figure 3:

System Volume Stack



The CSV Namespace Filter (CsvNsFlt.sys) is a file system mini-filter driver at an altitude of 404900:
>fltmc instances
Filter            Volume Name          Altitude      Instance Name
————  ———————  ————  ———————-
<skip>
CsvNSFlt      C:                             404900        CsvNSFlt Instance
<skip>


CsvNsFlt plays the following roles:

  • It protects C:\ClusterStorage by blocking unauthorized attempts that are not coming from the cluster service to delete or create any files or subfolders in this folder or change any attributes on the files. Other than opening these folders about the only other operation that is not blocked is renaming the folders. You can use command prompt or explorer to rename C:\ClusterStorage\Volume1 to something like C:\ClusterStorage\Accounting.  The directory name will be synchronized and updated on all nodes in the cluster.
  • It helps us to dispatch the block level redirected IO. We will cover this in more details when we talk about the block level redirected IO later on in this post.

The last stack we will look at is the stack of the CSV file system. Here you will see two modules CSV Volume Manager (csvvbus.sys), and CSV File System (CsvFs.sys). CsvFs is a file system driver, and mounts exclusively to the volumes surfaced up by CsvVbus.



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Cluster Shared Volume (CSV) Inside Out

Figure 5:

CsvFs stack

Data Flow


Now that we are familiar with the components and how they are related to each other, let’s look at the data flow.

First let’s look at how Metadata flows. Below you can see the same diagram as on the Figure 1. I’ve just kept only the arrows and blocks that is relevant to the metadata flow and removed the rest from the diagram.



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Cluster Shared Volume (CSV) Inside Out

Figure 6:

Metadata Flow



Our definition of metadata operation is everything except read and write. Examples of metadata operation would be create file, close file, rename file, change file attributes, delete file, change file size, any file system control, etc. Some writes may also, as a side effect cause a metadata change. For instance, an extending write will cause CsvFs to extend all or some of the following: file allocation size, file size and valid data length. A read might cause CsvFs to query some information from NTFS.

On the diagram above you can see that metadata from any node goes to the NTFS stack on Node 2. Data server nodes (Node 1 and Node 3) are using Server Message Block (SMB) as a protocol to forward metadata over.

Metadata are always forwarded to NTFS. On the coordinator node CsvFs will forward metadata IO directly to the NTFS volume while other nodes will use SMB to forward the metadata over the network.

Next, let’s look at the data flow for the Direct IO . The following diagram is produced from the diagram on the Figure 1 by removing any blocks and lines that are not relevant to the Direct IO. By definition Direct IO are the reads and writes that never go over the network, but go from CsvFs through CsvVbus straight to the disk stack. To make sure there is no ambiguity I’ll repeat it again: – Direct IO bypasses volume stack and goes directly to the disk.

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Cluster Shared Volume (CSV) Inside Out


Figure 7:

Direct IO Flow



Both Node 1 and Node 2 can see the shared disk – they can send reads and writes directly to the disk completely avoiding sending data over the network. The Node 3 is not in the diagram on the Figure 7 Direct IO Flow since it cannot perform Direct IO, but it is still part of the cluster and it will use block level redirected IO for reads and writes.

The next diagram shows a File System Redirected IO request flows. The diagram and data flow for the redirected IO is very similar to the one for the metadata from the Figure 6 Metadata Flow:



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Cluster Shared Volume (CSV) Inside Out

Figure 8
File System Redirected IO Flow



Later we will discuss when CsvFs uses the file system redirected IO to handle reads and writes and how it compares to what we see on the next diagram – Block Level Redirected IO :



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Cluster Shared Volume (CSV) Inside Out

Figure 9:

Block Level Redirected IO Flow



Note that on this diagram I have completely removed CsvFs stack and CSV NTFS stack from the Coordinator Node leaving only the system volume NTFS stack. The CSV NTFS stack is removed because Block Level Redirected IO completely bypasses it and goes to the disk (yes, like Direct IO it bypasses the volume stack and goes straight to the disk) below the NTFS stack. The CsvFs stack is removed because on the coordinating node CsvFs would never use Block Level Redirected IO, and would always talk to the disk. The reason why Node 3 would use Redirected IO, is because Node 3 does not have physical connectivity to the disk. A curious reader might wonder why Node 1 that can see the disk would ever use Block Level Redirected IO. There are at least two cases when this might be happening. Although the disk might be visible on the node it is possible that IO requests will fail because the adapter or storage network switch is misbehaving. In this case, CsvVbus will first attempt to send IO to the disk and on failure will forward the IO to the Coordinator Node using the Block Level Redirected IO. The other example is Storage Spaces – if the disk is a Mirrored Storage Space, then CsvFs will never use Direct IO on a data server node, but instead it will send the block level IO to the Coordinating Node using Block Level Redirected IO.  In Windows Server 2012 R2 you can use the Get-ClusterSharedVolumeState cmdlet to query the CSV state (direct / file level redirected / block level redirected) and if redirected it will state why.

Note that CsvFs sends the Block Level Redirected IO to the CsvNsFlt filter attached to the system volume stack on the Coordinating Node. This filter dispatches this IO directly to the disk bypassing NTFS and volume stack so no other filters below the CsvNsFlt on the system volume will see that IO. Since CsvNsFlt sits at a very high altitude, in practice no one besides this filter will see these IO requests. This IO is also completely invisible to the CSV NTFS stack. You can think about Block Level Redirected IO as a Direct IO that CsvVbus is shipping to the Coordinating Node and then with the help of the CsvNsFlt it is dispatched directly to the disk as a Direct IO is dispatched directly to the disk by CsvVbus.

What are these SMB shares?


CSV uses the Server Message Block (SMB) protocol to communicate with the Coordinator Node. As you know, SMB3 requires certain configuration to work. For instance it requires file shares. Let’s take a look at how cluster configures SMB to enable CSV.

If you dump list of SMB file shares on a cluster node with CSV volumes you will see following:
> Get-SmbShare
Name                  ScopeName           Path                        Description
——–                ————-           —-                          ———–
ADMIN$               *                           C:\Windows             Remote Admin
C$                         *                           C:\                           Default share
ClusterStorage$   CLUS030512         C:\ClusterStorage   Cluster Shared Volumes Def…
IPC$                      *                                                           Remote IPC


There is a hidden admin share that is created for CSV, shared as ClusterStorage$. This share is created by the cluster to facilitate remote administration. You should use it in the scenarios where you would normally use an admin share on any other volume (such as D$). This share is scoped to the Cluster Name. Cluster Name is a special kind of Network Name that is designed to be used to manage a cluster. You can learn more about Network Name in the following blog post.  You can access this share using the Cluster Name, i.e. \\<cluster name>\ClusterStorage$

Since this is an admin share, it is ACL’d so only members of the Administrators group have full access to this share. In the output the access control list is defined using Security Descriptor Definition Language (SDDL). You can learn more about SDDL here http://msdn.microsoft.com/en-us/library/windows/desktop/aa379567(v=vs.85).aspx
ShareState                        : Online
ClusterType                      : ScaleOut
ShareType                        : FileSystemDirectory
FolderEnumerationMode : Unrestricted
CachingMode                   : Manual
CATimeout                        : 0
ConcurrentUserLimit         : 0
ContinuouslyAvailable      : False
CurrentUsers                     : 0
Description                        : Cluster Shared Volumes Default Share
EncryptData                       : False
Name                                 : ClusterStorage$
Path                                   : C:\ClusterStorage
Scoped                              : True
ScopeName                       : CLUS030512
SecurityDescriptor             : D:(A;;FA;;;BA)


There are also couple hidden shares that are used by the CSV. You can see them if you add the IncludeHidden parameter to the get-SmbShare cmdlet. These shares are used only on the Coordinator Node. Other nodes either do not have these shares or these shares are not used:
> Get-SmbShare -IncludeHidden
Name                                           ScopeName         Path                                                  Description
—-                                               ———               —-                                                    ———–
17f81c5c-b533-43f0-a024-dc…    *                          \\?\GLOBALROOT\Device\Hard 
ADMIN$                                       *                          C:\Windows                                       Remote Admin
C$                                                 *                          C:\                                                      Default share
ClusterStorage$                           VPCLUS030512    C:\ClusterStorage                              Cluster Shared Volumes Def…
CSV$                                            *                           C:\ClusterStorage
IPC$                                             *                                                                                     Remote IPC


Each Cluster Shared Volume hosted on a coordinating node cluster creates a share with a name that looks like a GUID. This is used by CsvFs to communicate to the hidden CSV NTFS stack on the coordinating node. This share points to the hidden NTFS volume used by CSV. Metadata and the File System Redirected IO are flowing to the Coordinating Node using this share.
ShareState                           : Online
ClusterType                          : CSV
ShareType                            : FileSystemDirectory
FolderEnumerationMode    : Unrestricted
CachingMode                      : Manual
CATimeout                           : 0
ConcurrentUserLimit            : 0
ContinuouslyAvailable          : False
CurrentUsers                        : 0
Description                           :
EncryptData                          : False
Name                                    : 17f81c5c-b533-43f0-a024-dc431b8a7ee9-1048576$
Path                                      : \\?\GLOBALROOT\Device\Harddisk2\ClusterPartition1\
Scoped                                  : False
ScopeName                          : *
SecurityDescriptor                : O:SYG:SYD:(A;;FA;;;SY)(A;;FA;;;S-1-5-21-2310202761-1163001117-2437225037-1002)
ShadowCopy                         : False
Special                                   : True
Temporary                             : True


On the Coordinating Node you also will see a share with the name CSV$. This share is used to forward Block Level Redirected IO to the Coordinating Node. There is only one CSV$ share on every Coordinating Node:
ShareState                          : Online
ClusterType                         : CSV
ShareType                           : FileSystemDirectory
FolderEnumerationMode   : Unrestricted
CachingMode                     : Manual
CATimeout                          : 0
ConcurrentUserLimit           : 0
ContinuouslyAvailable         : False
CurrentUsers                       : 0
Description                          :
EncryptData                         : False
Name                                  : CSV$
Path                                     : C:\ClusterStorage
Scoped                                : False
ScopeName                         : *
SecurityDescriptor               : O:SYG:SYD:(A;;FA;;;SY)(A;;FA;;;S-1-5-21-2310202761-1163001117-2437225037-1002)
ShadowCopy                       : False
Special                                 : True
Temporary                           : True


Users are not expected to use these shares – they are ACL’d so only Local System and Failover Cluster Identity user (CLIUSR) have access to the share.

All of these shares are temporary – information about these shares is not in any persistent storage, and when node reboots they will be removed from the Server Service. Cluster takes care of creating the shares every time during CSV start up.

Conclusion


You can see that that Cluster Shared Volumes in Windows Server 2012 R2 is built on a solid foundation of Windows storage stack, CSVv1, and SMB3.

Thanks!
Vladimir Petter
Principal Software Development Engineer
Clustering & High-Availability
Microsoft

Additional Resources:


To learn more, here are others in the Cluster Shared Volume (CSV) blog series:

Cluster Shared Volume (CSV) Inside Out

Cluster Shared Volume Diagnostics

Cluster Shared Volume Performance Counters

Cluster Shared Volume Failure Handling

Troubleshooting Cluster Shared Volume Auto-Pauses – Event 5120

Troubleshooting Cluster Shared Volume Recovery Failure – System Event 5142

Cluster Shared Volume – A Systematic Approach to Finding Bottlenecks

Source :
https://techcommunity.microsoft.com/t5/failover-clustering/cluster-shared-volume-csv-inside-out/ba-p/371872