SoftSentryv211

Hunt Hypothesis

This detection identifies the execution of specific software binaries matching the SoftSentryv211 signature, which may indicate legitimate application usage or potential early-stage adversary activity involving known tools. Proactively hunting for this behavior in Azure Sentinel allows the SOC team to validate these occurrences against baseline patterns and quickly distinguish between routine operations and subtle indicators of compromise that could evolve into larger threats.

YARA Rule

rule SoftSentryv211
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 55 8B EC 83 EC ?? 53 56 57 E9 50 }

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 5 specific false positive scenarios for the SoftSentryv211 detection rule, including suggested filters and exclusions tailored for an enterprise environment:

• Scenario: Legitimate execution of Microsoft Defender Antivirus signature updates.

  • Context: The MsMpEng.exe process frequently triggers this YARA rule when it downloads and installs new virus definition packs via the scheduled “Update” task, often mimicking the behavior patterns SoftSentryv211 is designed to catch.
  • Filter/Exclusion: Exclude processes where the executable path matches C:\Program Files\Windows Defender\MsMpEng.exe AND the parent process is WUAuserv.exe.

• Scenario: Automated deployment of software patches via SCCM (System Center Configuration Manager).

  • Context: During nightly maintenance windows, the SCCM client service (ccmexec.exe) launches installation scripts that modify registry keys and inject code into running applications, which can be flagged as anomalous by SoftSentryv211.
  • Filter/Exclusion: Create a whitelist for the process name ccmexec.exe when it is spawned by the parent TaskScheduler.exe with the specific command line argument containing /deploy.

• Scenario: Routine backup operations performed by Veeam Backup & Replication.

  • Context: The Veeam transport service (VeeamTransportService.exe) performs heavy I/O and memory mapping activities during incremental backups, which often triggers the heuristic logic of this rule due to its interaction with system DLLs.
  • Filter/Exclusion: Exclude events where the process image hash matches the known good hash for C:\Program Files\Veeam\Backup and Replication\TransportService.exe running under the user context VeeamBackupSvc.

• Scenario: Execution of PowerShell