Scarhikn code features

Hunt Hypothesis

This detection rule identifies anomalous code execution patterns associated with the Scarhikn threat actor, specifically targeting unique behavioral signatures that may indicate early-stage reconnaissance or lateral movement within cloud workloads. Proactively hunting for these features in Azure Sentinel is critical to validate low-severity alerts before they escalate, ensuring that subtle indicators of compromise are not overlooked amidst routine operational noise.

YARA Rule

rule ScarhiknCode : Scarhikn Family 
{
    meta:
        description = "Scarhikn code features"
        author = "Seth Hardy"
        last_modified = "2014-06-25"
    
    strings:
        // decryption
        $ = { 8B 06 8A 8B ?? ?? ?? ?? 30 0C 38 03 C7 55 43 E8 ?? ?? ?? ?? 3B D8 59 72 E7 }
        $ = { 8B 02 8A 8D ?? ?? ?? ?? 30 0C 30 03 C6 8B FB 83 C9 FF 33 C0 45 F2 AE F7 D1 49 3B E9 72 E2 }
    
    condition:
        any of them
}

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
• Source Rule

False Positive Guidance

Here are 5 specific false positive scenarios for the Scarhikn code features detection rule in an enterprise environment, including suggested filters and exclusions:

• Scheduled Antivirus Database Updates via SCCM

  • Scenario: The System Center Configuration Manager (SCCM) deploys a nightly update to the endpoint protection suite (e.g., Microsoft Defender for Endpoint or CrowdStrike). During this process, the agent updates its signature database and scans specific “code feature” directories, triggering the rule due to high-frequency file attribute changes.
  • Filter/Exclusion: Exclude processes running under ccmexec.exe or mpcmdrun.exe where the parent process is TaskScheduler. Additionally, filter out events occurring strictly between 02:00 and 04:00 UTC to align with maintenance windows.

• CI/CD Pipeline Artifact Generation

  • Scenario: A Jenkins or GitLab CI runner executes a build job that compiles source code and generates temporary artifacts in the shared network storage (e.g., Azure Files or NetApp). The compilation tools (like msbuild.exe or javac) create numerous new files with specific metadata tags that mimic the “Scarhikn” feature signature.
  • Filter/Exclusion: Create a whitelist for known CI service accounts (e.g., svc-jenkins-build, gitlab-runner). Filter events where the source IP belongs to the internal build subnet (e.g., 10.20.30.0/24) and the destination path matches the artifact repository pattern (\\build-server\artifacts\*).

• Enterprise Software Patching via WSUS

  • Scenario: Windows Server Update Services (WSUS) pushes a critical security patch to a fleet of file servers. The installation process modifies system libraries and registry keys associated with code execution