Detects BlackEnergy 2 Malware

Hunt Hypothesis

The hypothesis is that the detection of BlackEnergy 2 Malware indicates an adversary is leveraging advanced persistent threat tactics to establish a foothold in the network. A SOC team should proactively hunt for this behavior in Azure Sentinel to identify and mitigate potential long-term compromise and exfiltration activities.

YARA Rule

rule BlackEnergy_BE_2 
{
   
   meta:
      description = "Detects BlackEnergy 2 Malware"
      author = "Florian Roth"
      reference = "http://goo.gl/DThzLz"
      date = "2015/02/19"
      hash = "983cfcf3aaaeff1ad82eb70f77088ad6ccedee77"
   
   strings:
      $s0 = "<description> Windows system utility service  </description>" fullword ascii
      $s1 = "WindowsSysUtility - Unicode" fullword wide
      $s2 = "msiexec.exe" fullword wide
      $s3 = "WinHelpW" fullword ascii
      $s4 = "ReadProcessMemory" fullword ascii
   
   condition:
      uint16(0) == 0x5a4d and filesize < 250KB and all of ($s*)
}

Deployment Notes

This YARA rule can be deployed in the following contexts:

• Microsoft Defender for Endpoint — Custom indicators / advanced hunting
• Email Gateway — Attachment scanning
• File Share Monitoring — Periodic scanning of shared drives
• YARA CLI — Manual threat hunting on endpoints

This rule contains 5 string patterns in its detection logic.

References

• http://goo.gl/DThzLz
• Source Rule

False Positive Guidance

• Scenario: Legitimate scheduled backup job using Veeam Backup & Replication
  Filter/Exclusion: Exclude processes associated with veeam.exe or check for the presence of backup in the command line arguments.

• Scenario: System administrator running PowerShell scripts for routine system maintenance
  Filter/Exclusion: Exclude processes with powershell.exe where the command line includes -Command or -File and the script path is known to be internal (e.g., C:\Windows\System32\WindowsPowerShell\v1.0\).

• Scenario: Use of Microsoft Sysinternals tools (e.g., Process Explorer, Procmon) for troubleshooting
  Filter/Exclusion: Exclude processes with procmon.exe, process.explorer.exe, or other Sysinternals executables.

• Scenario: Execution of Windows Task Scheduler jobs for software updates or patches
  Filter/Exclusion: Exclude processes launched by schtasks.exe or with the command line containing schtasks or Task Scheduler.

• Scenario: Legitimate use of Windows Event Log tools (e.g., eventvwr.exe) for log analysis
  Filter/Exclusion: Exclude processes with eventvwr.exe or check for the presence of eventlog or event viewer in the command line.