Upack021betaDwing

Hunt Hypothesis

This detection identifies potential malicious activity where adversaries utilize specific unpacking mechanisms to execute hidden payloads within the environment. Proactive hunting for this behavior is essential in Azure Sentinel to uncover stealthy threats that may evade standard signature-based defenses by analyzing low-severity YARA matches before they escalate into larger incidents.

YARA Rule

rule Upack021betaDwing
{
      meta:
		author="malware-lu"
strings:
		$a0 = { BE 88 01 40 00 AD 8B F8 6A 04 95 A5 33 C0 AB 48 AB F7 D8 59 F3 AB C1 E0 0A B5 ?? F3 AB AD 50 97 51 58 8D 54 85 5C FF 16 72 5A 2C 03 73 02 B0 00 3C 07 72 02 2C 03 50 0F B6 5F FF C1 E3 ?? B3 00 }

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 Upack021betaDwing detection rule, including targeted filters and exclusions:

• Scenario: Automated deployment of software updates via Microsoft Endpoint Configuration Manager (SCCM) or Intune.

  • Context: When the system pushes a new application package to endpoints, the installer often extracts compressed archives (e.g., .msi or .cab) containing nested DLLs that match the signature pattern of the rule. This is common during nightly maintenance windows.
  • Suggested Filter/Exclusion: Exclude processes spawned by ccmsetup.exe, wsman.exe, and msiexec.exe when running under the context of the “System” account or specific service accounts (e.g., DOMAIN\SCCM-Deploy).

• Scenario: Execution of scheduled backup jobs using Veeam Backup & Replication or Acronis Cyber Protect.

  • Context: During the initial phase of a full backup, these tools unpack large virtual machine images or compressed data blocks into temporary staging directories. The YARA rule may flag the extraction engine’s memory footprint as a potential unpacking anomaly.
  • Suggested Filter/Exclusion: Create an exclusion for file paths located in dedicated backup staging folders (e.g., C:\Program Files\Veeam\Backup\Staging or D:\Acronis\Temp) and exclude the parent process names Veeam.Backup.Service.exe and acronis_backup_agent.exe.

• Scenario: Development environment activity involving Visual Studio or Jenkins CI/CD pipelines.

  • Context: Developers frequently run local builds where the build server unpacks NuGet packages, Docker images, or JAR files. The rule might trigger when the build agent extracts these artifacts into a workspace directory, mist