EXECryptor224StrongbitSoftCompleteDevelopmenth3

Hunt Hypothesis

This hunt detects the execution of a specific executable associated with StrongBit Software’s development environment, potentially indicating legitimate software deployment or an adversary leveraging trusted application processes to establish persistence. A proactive search in Azure Sentinel is recommended to distinguish this benign activity from potential masquerading attacks where threat actors mimic known development tools to evade initial detection and execute malicious payloads within the organization’s infrastructure.

YARA Rule

rule EXECryptor224StrongbitSoftCompleteDevelopmenth3
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 6B 65 72 6E 65 6C 33 32 2E 64 6C 6C 00 00 00 00 00 00 47 65 74 4D 6F 64 75 6C 65 48 61 6E 64 6C 65 41 00 00 00 00 4C 6F 61 64 4C 69 62 72 61 72 79 41 00 00 00 00 47 65 74 50 72 6F 63 41 64 64 72 65 73 73 00 00 00 00 00 00 45 78 69 74 50 72 6F 63 65 73 73 }

condition:
		$a0
}

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

• Scenario: The StrongBit development team runs nightly automated builds using their proprietary build server (BuildServer-01). During the “Complete Development” phase of the CI/CD pipeline, the msbuild.exe process invokes a custom encryption utility to seal source artifacts before archiving. This triggers the rule due to the specific string signature in the executable’s header matching the YARA pattern for StrongBit’s development tools.

  • Filter/Exclusion: Create an exclusion based on the parent process name msbuild.exe and the command line argument containing /p:StrongBitEncrypt=true. Alternatively, whitelist the specific file path C:\Program Files\StrongBit\BuildTools\sb_encryptor.exe if it resides in a known trusted directory.

• Scenario: The IT Operations team utilizes Microsoft System Center Configuration Manager (SCCM) to deploy a new security patch across the enterprise. A scheduled task named “SB_Dev_Complete_Job” executes on domain-joined workstations at 02:00 AM, launching a local script that invokes the StrongBit encryption module to verify and seal application logs before transmission to the SIEM.

  • Filter/Exclusion: Implement a filter excluding events where the User account is SYSTEM or a specific service account (e.g., svc-sccm-agent) AND the process path matches C:\Program Files\Microsoft Configuration Manager\AdminConsole\Tools\sb_complete_dev.exe.

• Scenario: The DevOps group utilizes Jenkins running on a dedicated host (jenkins-node-04). When a pipeline stage labeled “Complete Development” reaches the final commit step, Jenkins triggers a webhook that calls an external StrongBit API wrapper. This wrapper executes locally to encrypt the build artifacts before pushing them to the artifact repository, generating the specific YARA signature match.

  • Filter/Exclusion: