Armadillov2xxCopyMemII

Hunt Hypothesis

This detection identifies adversary behavior involving in-memory code execution and memory manipulation consistent with the Armadillo v2.x copy mechanism, often utilized by malware to evade disk-based analysis. A SOC team should proactively hunt for this pattern in Azure Sentinel to uncover stealthy threats that rely on process hollowing or reflective loading techniques to establish persistence without leaving traditional file system artifacts.

YARA Rule

rule Armadillov2xxCopyMemII
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 6A ?? 8B B5 [4] C1 E6 04 8B 85 [4] 25 07 [2] 80 79 05 48 83 C8 F8 40 33 C9 8A 88 [4] 8B 95 [4] 81 E2 07 [2] 80 79 05 4A 83 CA F8 42 33 C0 8A 82 }

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 Armadillov2xxCopyMemII detection rule, along with recommended filters and exclusions:

• Scenario: Legitimate execution of Microsoft Office Click-to-Run (OfficeClickToRun.exe) during background updates or document rendering.

  • Context: The Office suite frequently utilizes memory copying mechanisms to handle large documents or apply patches via the mscorsvw.exe helper process, which mimics the behavior of Armadillo’s memory manipulation.
  • Filter/Exclusion: Exclude processes where the image path contains \Microsoft Office\ClickToRun\OfficeClickToRun.exe and the parent process is svchost.exe or mscorsvw.exe.

• Scenario: Scheduled backup jobs running via Veeam Backup & Replication (VeeamBackupService.exe).

  • Context: During incremental backups, Veeam reads application memory states to capture transaction logs, triggering high-frequency memory copy operations that align with the YARA rule’s signature.
  • Filter/Exclusion: Create an exclusion for VeeamBackupService.exe running under the context of the “System” or a dedicated backup service account (e.g., DOMAIN\VeeamSvc) during defined maintenance windows (e.g., 02:00–06:00).

• Scenario: Deployment and configuration tasks performed by Microsoft Endpoint Configuration Manager (ConfigMgr/SCCM) using the ccmexec.exe agent.

  • Context: When SCCM pushes software updates or configuration policies, the client agent often copies large memory blocks to apply changes, which can be misidentified as malicious memory injection.
  • Filter/Exclusion: Filter out events where the process name is ccmexec.exe and the parent process is `wuaus