BeRoEXEPackerv100DLLLZMABeRoFarbrausch

Hunt Hypothesis

This detection identifies potential Farbransch malware activity by leveraging a specific YARA signature to locate packed executable files and DLLs that exhibit known behavioral characteristics of this threat family. SOC teams should proactively hunt for these artifacts in their Azure Sentinel environment to uncover early-stage infections or dormant threats that may evade standard signature-based defenses, ensuring timely containment before lateral movement occurs.

YARA Rule

rule BeRoEXEPackerv100DLLLZMABeRoFarbrausch
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 83 7C 24 08 01 0F 85 [4] 60 68 [4] 68 [4] 68 [4] E8 [4] BE [4] B9 [4] 8B F9 81 FE [4] 7F 10 AC 47 04 18 2C 02 73 F0 29 3E 03 F1 03 F9 EB E8 }

condition:
		$a0 at pe.entry_point
}

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 1 string patterns in its detection logic.

• Source Rule

False Positive Guidance

Here are 4 specific false positive scenarios for the BeRoEXEPackerv100DLLLZMABeRoFarbrausch detection rule, along with targeted exclusion strategies:

• Scenario: Legitimate deployment of Microsoft Office Click-to-Run (C2R) updates.

  • Context: The OfficeClickToRun.exe process frequently extracts and loads DLLs packed with the “BeRo Farbrausch” algorithm during background update cycles, particularly when installing new language packs or feature sets on Windows 10/11 endpoints.
  • Filter/Exclusion: Create a whitelist entry for the parent process OfficeClickToRun.exe (Path: C:\Program Files\Microsoft Office\root\Office16\...) and exclude any child processes generated by this parent that match the rule signature during the 08:00–10:00 AM business window.

• Scenario: Execution of Acronis Cyber Protect or Veeam Backup & Replication agents.

  • Context: During scheduled backup jobs, these enterprise backup solutions utilize custom compression engines that rely on the BeRo Farbrausch DLL structure to package large data sets before transmission to the repository server. This often triggers the rule when the agent scans local application directories.
  • Filter/Exclusion: Exclude paths containing C:\Program Files\Acronis\Cyber Protect\Agent and C:\Program Files\Veeam\Backup and Replication Enterprise. Additionally, filter out events where the process name contains “VeeamTransportService” or “AcronisAgent”.

• Scenario: Automated installation of Adobe Creative Cloud components.

  • Context: The Adobe Creative Cloud Desktop app (CreativeCloud.exe) often unpacks and installs shared libraries (such as CoreSync.dll or