Rooter code features

Hunt Hypothesis

This detection rule identifies anomalous rooter code execution patterns that may indicate early-stage persistence mechanisms or unauthorized system modifications within Azure workloads. Proactively hunting for these low-severity signals in Azure Sentinel allows the SOC team to distinguish benign operational activities from subtle adversary footholds before they escalate into critical incidents.

YARA Rule

rule RooterCode : Rooter Family 
{
    meta:
        description = "Rooter code features"
        author = "Seth Hardy"
        last_modified = "2014-07-10"
    
    strings:
        // xor 0x30 decryption
        $ = { 80 B0 ?? ?? ?? ?? 30 40 3D 00 50 00 00 7C F1 }
    
    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 Rooter code features detection rule in an enterprise environment, along with suggested filters or exclusions:

• Antivirus Real-Time Scanning and Engine Updates

  • Scenario: Enterprise Endpoint Protection suites (e.g., CrowdStrike Falcon, Microsoft Defender for Endpoint) frequently inject code into running processes to scan memory or update their own detection engines. This often manifests as legitimate “rooter” behavior where the AV service modifies its own executable or creates new hooks in system memory.
  • Filter/Exclusion: Create an exclusion rule that whitelists known Antivirus vendor process names (e.g., MsMpEng.exe, CsFalconService.exe) and restricts alerts to only those originating from the specific installation directories of these tools (e.g., C:\Program Files\Microsoft Defender\).

• Scheduled System Patching and Maintenance Jobs

  • Scenario: Automated patch management systems like WSUS, SCCM (System Center Configuration Manager), or Ansible Tower execute scheduled tasks during maintenance windows. These jobs often involve installing updates that require modifying system binaries, injecting code into the kernel, or restarting services to apply patches, triggering rooter logic signatures.
  • Filter/Exclusion: Implement a time-based filter to suppress alerts for this rule between 02:00 and 06:00 (local server time) on weekdays. Additionally, exclude process paths containing standard patching tool identifiers such as ccmexec.exe or ansible-runner.

• Database Engine Optimization and Index Rebuilding

  • Scenario: Database administrators running maintenance scripts on SQL Server or Oracle instances often trigger code injection to rebuild indexes or optimize query execution plans. Tools like SQL Server Management Studio (SSMS) or automated backup agents may modify memory structures in a way that mimics rooter activity, especially when the