Upack024027beta028alphaDwing

Hunt Hypothesis

This YARA rule targets specific unpacking or obfuscation patterns often associated with low-severity malware variants, indicating potential attempts to hide malicious code from static analysis. Proactively hunting for these signatures allows the SOC team to identify stealthy payloads that may be evading traditional detection methods before they can establish a foothold in the environment.

YARA Rule

rule Upack024027beta028alphaDwing
{
      meta:
		author="malware-lu"
strings:
		$a0 = { BE 88 01 40 00 AD 8B F8 95 AD 91 F3 A5 AD B5 ?? F3 AB AD 50 97 51 58 8D 54 85 5C FF 16 72 57 2C 03 73 02 B0 00 3C 07 72 02 2C 03 50 0F B6 5F FF C1 E3 ?? B3 00 8D 1C 5B 8D 9C 9D 0C 10 00 00 B0 }

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

• Antivirus/EDR Engine Updates: When the endpoint protection agent (e.g., CrowdStrike Falcon, Microsoft Defender for Endpoint, or SentinelOne) pushes a new signature pack or engine update, it may temporarily write or modify the Dwing (Dynamic Window) cache or associated memory structures during the initialization of the new detection modules.
  • Filter/Exclusion: Exclude processes where the parent process is the AV/EDR service (e.g., CldFltMon.exe, FalconSensor.exe, SentinelOneAgent.exe) and the file path resides in the vendor’s specific installation directory (e.g., C:\Program Files\CrowdStrike\).
• Browser Extension or Plugin Loading: Modern browsers (Chrome, Edge, Firefox) load native code plugins or extensions that utilize dynamic windowing for UI rendering or hardware acceleration. If a YARA rule scans loaded DLLs or memory regions, legitimate browser helper processes (e.g., chrome_crashpad_handler.exe, msedgewebview2.exe) might trigger the rule if they contain specific binary patterns associated with the Dwing structure.
  • Filter/Exclusion: Exclude processes where the executable name matches known browser helper binaries (chrome.exe, msedge.exe, firefox.exe and their child processes) and the image path is within the browser’s standard installation directory (e.g., C:\Program Files (x86)\Google\Chrome\).
• Game Launcher or Media Player Initialization: Applications like Steam, Epic Games Launcher, or VLC Media Player often use complex UI frameworks that rely on dynamic window management. During startup or when switching between views (e.g., library vs. store), these applications may allocate or modify memory regions that match the YARA pattern for Dwing.
  • Filter/Exclusion: Exclude processes where the parent process is a known game