Upack010012betaDwing

Hunt Hypothesis

This detection identifies potential malicious activity where adversaries attempt to unpack or execute files matching the specific “Upack010012betaDwing” YARA signature, which may indicate early-stage file extraction by unknown malware variants. A proactive hunt is essential in Azure Sentinel to validate these low-severity events against baseline behavior and prevent the silent establishment of persistence mechanisms before they escalate into higher-impact incidents.

YARA Rule

rule Upack010012betaDwing
{
      meta:
		author="malware-lu"
strings:
		$a0 = { BE 48 01 40 00 AD 8B F8 95 A5 33 C0 33 C9 AB 48 AB F7 D8 B1 04 F3 AB C1 E0 0A B5 ?? F3 AB AD 50 97 51 AD 87 F5 58 8D 54 86 5C FF D5 72 5A 2C 03 73 02 B0 00 3C 07 72 02 2C 03 50 0F B6 5F FF C1 }

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 3-5 specific false positive scenarios for the Upack010012betaDwing detection rule, including suggested filters and exclusions:

• Scenario: Scheduled Antivirus Definition Updates via GPO

  • Context: Enterprise endpoints often receive daily definition updates pushed via Group Policy Objects (GPO). When tools like Microsoft Defender for Endpoint, Symantec Endpoint Protection, or Carbon Black unpack the update payload to extract new signatures, the extraction process mimics the behavior of a malicious archive unpacking event.
  • Suggested Filter/Exclusion: Create an exclusion based on the specific Process Name (e.g., MsMpEng.exe, SymantecEngine.exe) and restrict the rule trigger to only fire when the parent process is not one of these known security agents. Additionally, exclude file paths matching the vendor’s update directory (e.g., C:\ProgramData\Microsoft\Windows Defender\Updates).

• Scenario: Software Deployment via Configuration Management Tools

  • Context: During business hours or maintenance windows, IT administrators use tools like Microsoft Endpoint Configuration Manager (MECM/SCCM), Jamf, or Ansible to deploy applications. These tools frequently download and unpack .msi, .exe, or .zip installers into temporary directories (%TEMP% or C:\Windows\Temp) before execution, triggering the “unpacking” logic of the YARA rule.
  • Suggested Filter/Exclusion: Implement a path-based exclusion for known deployment directories (e.g., C:\Windows\CCMCache, C:\ProgramData\Microsoft\MSCCM). Furthermore, add a filter to exclude events where the parent process is ccmexec.exe (SCCM) or JamfProAgent.exe.

• **Scenario: Automated Backup and