McAfee is aware of a new variant of ransomware that has been detected in corporate environments. Threat Name:
Ransom-WannaCry (also known as
WCry,
WanaCrypt,
WannaCrypt, and WanaCrypt0r).
Read McAfee observations and analysis here:
https://securingtomorrow.mcafee.com/business/analysis-wannacry-ransomware-outbreak/
Read the official McAfee Threat Advisory here:
KB91863 - Threat Advisory: Ransom-WannaCry.
See also the information in this Technical Brief:
https://www.mcafee.com/us/resources/solution-briefs/sb-how-to-protect-against-ransomware.pdf
Minimum DATs for coverage:
- Endpoint Security (ENS) 2978 or higher *
- VirusScan Enterprise (VSE) 8527 or higher *
* McAfee-defined content protection against known variants.
As a best practice, configure repository update tasks with a minimal refresh interval. This practice makes sure that new content is applied when McAfee releases it.
This article gets updated as and when the additional information is available. Continue to monitor this article for updates.
Topics in this article
Symptoms of infected systems
VSE Access Protection rules
ENS Access Protection rules
ENS Adaptive Threat Protection – Real Protect and Dynamic Application Containment
ENS Dynamic Application Containment rules
Advanced Threat Defense coverage for WannaCry Ransomware
McAfee NSP coverage for WannaCry Ransomware
Frequently Asked Questions
Recent updates to this article
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Date |
Update |
September 22, 2020 |
Added new Endpoint Security Adaptive Threat Protection category. |
March 12, 2020 |
Replaced "daily DAT" with "Regular DAT". |
September 9, 2019 |
The link for the Ransom-WannaCry Threat Advisory was changed to KB91863. |
November 20, 2017 |
Removed Extra.DAT file attachment and references to the Extra.DAT file. |
This threat exhibits the following symptoms on infected systems:
- Files are encrypted with the .wnry, .wcry, .wncry, .wcryt, and .wncryt extension. Users see a screen with a ransom message.
- Users see the following Ransom-WannaCry Desktop Background:
- On restarting, impacted systems have a blue screen error and can't start.
- Encryption seen on local host and open SMB shares. IMPORTANT: Immediately install the Critical Microsoft Patch MS17-010, to prevent SMB shares from becoming encrypted: https://technet.microsoft.com/en-us/library/security/ms17-010.aspx.
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Endpoint Security (ENS) and VirusScan Enterprise (VSE) Access Protection Proactive Measures
NOTE: The ENS and VSE Access Protection rules prevent creation of the .WNRY file. This rule prevents the encryption routine, which is where you see the encrypted files that contain one or more .WNCRYT, .WNCRY, or .WCRY extensions. By implementing the block against .WNRY, other blocks are not needed for the encrypted file types. |
Use VSE Access Protection rules:
Rule1:
Rule Type: Registry Blocking Rule
Process to include: *
Registry key or value to protect: HKLM - /Software/WanaCrypt0r
Registry key or value p protect: Key
File actions to prevent: Create key or value

Rule2:
Rule Type: File/Folder Blocking Rule
Process to include: *
File or folder name to block: *.wnry
File actions to prevent: New files being created

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Use ENS Access Protection rules:
Rule1:
Executable1:
Inclusion: Include
File Name or Path: *

SubRule1:
SubRule Type: Registry key
Operations: Create
Target1:
Inclusion: Include
File, folder name, or file path: *\Software\WanaCrypt0r

SubRule2:
SubRule Type: Files
Operations: Create
Target1:
Inclusion: Include
File, folder name, or file path: *.wnry

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Endpoint Security (ENS) with Adaptive Threat Protection (ATP) – Real Protect and Dynamic Application Containment (DAC)
ENS ATP Real Protect, with DAC, provides next-generation protection against unknown exploits.
ENS ATP provides full protection against all known variants of the WannaCry exploit. McAfee recommends the following ATP configuration for detection of unknown WannaCry variants.
- Configure the following setting in the Adaptive Threat Protection - Options Policy:
Rule Assignment = Security (default setting is Balanced)

- Configure the following rules in the Adaptive Threat Protection – Dynamic Application Containment policy:
Dynamic Application Containment – Containment Rules
See KB87843 - List of and best practices for Endpoint Security Dynamic Application Containment rules, and set the recommended DAC rules to Block as prescribed.

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ENS DAC rules triggered by Ransom-WannaCry variants
This section provides additional information about observed DAC rules triggered by known WannaCry variants. For processes that other layers of the ENS security stack do not detect, extra rule enablement might not be needed to effectively contain the processes. See KB87843 - Best Practices for ENS Dynamic Application Containment Rues, and set the recommended DAC rules to Block as prescribed.
Rule1:
Rule Name: Executing any child process
Rule2:
Rule Name: Accessing user cookie locations
Rule3:
Rule Name: Creating files with the .html, .jpg, or .bmp extension
Rule4:
Rule Name: Creating files with the .exe extension
Rule5:
Rule Name: Modifying users' data folders
Rule6:
Rule Name: Modifying startup registry locations
Rule7:
Rule Name: Modifying critical Windows files and registry locations
Rule8:
Rule Name: Reading or modifying files on any network location
Rule9:
Rule Name: Modifying files with the .bat extension
Rule10:
Rule Name: Modifying files with the .vbs extension
Rule11:
Rule Name: Creating files with the .bat extension
Rule12:
Rule Name: Reading files commonly targeted by ransomware-class malware
Rule13:
Rule Name: Creating files on any network location
Rule14:
Rule Name: Writing to files commonly targeted by ransomware-class malware
Rule15:
Rule Name: Modifying the hidden attribute bit
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Advanced Threat Defense (ATD) Content Update Package for WannaCry available in the following builds, or later:
3.6.x – 3.6.2.103.61987 or later
3.8.x package – 3.8.2.170207.59307 or later
3.10.x – 3.10.2.170712.61985 or later
4.0 – Detection included in base install
McAfee NSP coverage for WannaCry Ransomware:
Existing signatures:
- 0x43c0b800- NETBIOS-SS: Windows SMBv1 identical MID and FID type confusion vulnerability (CVE-2017-0143)
- 0x43c0b400- NETBIOS-SS: Windows SMB Remote Code Execution Vulnerability (CVE-2017-0144)
- 0x43c0b500- NETBIOS-SS: Windows SMB Remote Code Execution Vulnerability (CVE-2017-0145)
- 0x43c0b300- NETBIOS-SS: Microsoft Windows SMB Out of bound Write Vulnerability (CVE-2017-0146)
- 0x43c0b900- NETBIOS-SS: Windows SMBv1 information disclosure vulnerability (CVE-2017-0147)
The NSP Research Team has reviewed the information for CVE-2017-0148 and has created a UDS. The UDS is available from
KB55447 - REGISTERED - Network Security Platform User-Defined Signature Releases. This article is available only to registered users. Log on to
https://support.mcafee.com and access the article.
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Frequently Asked Questions about Ransom-WannaCry
Does having McAfee Application Control (MAC) in block mode help prevent the infection?
Yes, because MAC blocks any new hash values that are not in the allow list.
Does a combination of Threat Intelligence Exchange (TIE) and ATD blocks this threat on Day 0?
TIE and ATD contained several 0-day WannaCry samples. For those samples that were missed, further intelligence was added to the cloud, that picked up subsequent WannaCry variants as 0-day. ATD also released content updates that were specific to WannaCry. These content updates are available in current builds.
Why are you naming the Access Protection rules generically?
Rule names make no impact on the rule itself and can be named anything you want.
Why doesn't the software key use ‘\’ and not ‘/’?
‘\’ is the correct syntax one would enter, but the managed product modifies the path and replaces all ‘\’ with ‘/’. So, that is the reason behind this syntax.
Why isn't the file extension rule: **\*.wnry?
No. Because ENS and VSE use different wildcard syntax, it is best to use
*.wnry, as both can use this rule properly.
What Regular DAT file is coverage released in?
ENS DAT 2978 or later
VSE DAT 8527 or later