PECompactv25RetailBitsumTechnologies

Hunt Hypothesis

This detection identifies potentially malicious or obfuscated executable files utilizing Bitsum Technologies’ PECompact v25 retail compression method, which adversaries often employ to reduce file size and evade signature-based scanning. SOC teams should proactively hunt for these artifacts in Azure Sentinel to uncover stealthy malware that leverages this specific packing technique to bypass initial security controls and establish a foothold within the environment.

YARA Rule

rule PECompactv25RetailBitsumTechnologies
{
      meta:
		author="malware-lu"
strings:
		$a0 = { B8 [3] 01 50 64 FF 35 00 00 00 00 64 89 25 00 00 00 00 33 C0 89 08 50 45 43 6F 6D 70 61 63 74 32 00 }

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 PECompactv25RetailBitsumTechnologies detection rule, including targeted filters and exclusions:

• Scenario: Deployment of Bitdefender GravityZone Endpoint Security Agents

  • Context: During a scheduled patching window or new workstation provisioning, the IT team deploys the latest version of Bitdefender GravityZone agents. The installer (bdagent.exe or bdvtool.exe) utilizes the PECompact v25 compression format for its retail build binaries to reduce disk footprint during installation.
  • Filter/Exclusion: Exclude processes originating from the C:\Program Files\Bitdefender\GravityZone\ directory path, specifically targeting executable names containing bdagent, bdvtool, or bdservice. Additionally, exclude events where the parent process is msiexec.exe running with the /qn (quiet) switch during maintenance windows.

• Scenario: Execution of Retail Software Updates via SCCM/Intune

  • Context: System Center Configuration Manager (SCCM) or Microsoft Intune pushes a retail update package for a third-party enterprise application (e.g., Adobe Acrobat Pro DC or Microsoft Office 365). The update payload is compressed using the Bitsum Technologies PECompact v25 algorithm before being unpacked and executed on the endpoint.
  • Filter/Exclusion: Create an exclusion based on the parent process name ccmexec.exe (SCCM) or Microsoft.IntuneManagementAgent. Filter for file hashes that match known good signatures of the specific retail update package, or exclude files located within the C:\Windows\CCM\Logs\ and C:\Program Files\Apps\RetailUpdates\ directories.

• Scenario: Scheduled Backup Jobs Using Bitdefender Endpoint Protection

  • Context: A nightly scheduled