DBPEv153

Hunt Hypothesis

This detection identifies specific malware or suspicious artifacts matching the DBPEv153 YARA signature within Azure Sentinel workloads to uncover potential early-stage threats that may evade standard heuristic defenses. Proactively hunting for this indicator allows the SOC team to validate low-severity alerts in real-time, ensuring that subtle signs of compromise are escalated before they evolve into significant incidents.

YARA Rule

rule DBPEv153
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 9C 55 57 56 52 51 53 9C FA E8 [4] 5D 81 ED 5B 53 40 ?? B0 ?? E8 [4] 5E 83 C6 11 B9 27 [3] 30 06 46 49 75 FA }

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 DBPEv153 detection rule, including targeted filters and exclusions suitable for an enterprise environment:

• Scenario: Scheduled Antivirus Scans on Database Servers

  • Context: Enterprise antivirus solutions like Microsoft Defender for Endpoint or Symantec Endpoint Protection often run scheduled deep scans on SQL Server instances during off-hours. The YARA rule may flag the heavy I/O and process spawning behavior of these scans as suspicious database activity, particularly if the scan engine injects code into the sqlservr.exe process.
  • Filter/Exclusion: Create a filter to exclude alerts where the parent process is MsMpEng.exe (Defender) or Symantec Endpoint Protection Client, and the source IP belongs to the internal management subnet (e.g., 10.20.x.x).

• Scenario: Automated Backup Jobs via PowerShell Scripts

  • Context: IT operations teams frequently utilize PowerShell scripts executed by System Center Configuration Manager (SCCM) or Azure Automation Accounts to perform nightly database backups and integrity checks (DBCC CHECKDB). These scripts often invoke the sqlcmd utility or connect directly via ODBC, triggering the rule’s logic regarding external connections or script execution within the DB context.
  • Filter/Exclusion: Exclude events where the command line contains specific backup keywords (e.g., -BackupAction, BACKUP DATABASE) and the user account is a dedicated service account named svc-db-backup or SCCM-DB-Agent.

• Scenario: ETL Processes Running via T-SQL Agent Jobs

  • Context: Data warehousing teams use SQL Server Agent to run complex Extract, Transform, Load (ETL) jobs using tools like Tally or custom stored procedures. These