Armadillov260b2

Hunt Hypothesis

This detection identifies the presence of the Armadillo malware variant (v260b2) by matching file signatures against a specific YARA rule within the Azure Sentinel environment. Proactively hunting for this behavior is essential to uncover early-stage infections that may exhibit low severity initially but could evolve into significant threats if left unmonitored in cloud workloads.

YARA Rule

rule Armadillov260b2
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 55 8B EC 6A FF 68 90 [3] 68 24 [3] 64 A1 [4] 50 64 89 25 [4] 83 EC 58 53 56 57 89 65 E8 FF 15 60 [3] 33 D2 8A D4 89 15 3C }

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 Armadillov260b2 detection rule, along with targeted filters and exclusions suitable for an enterprise environment:

• Scenario: Scheduled Endpoint Protection Scans

  • Context: The YARA rule triggers when major security suites perform routine signature database updates or full system scans. Specifically, CrowdStrike Falcon or Microsoft Defender for Endpoint often execute the Armadillo payload during their nightly maintenance windows (e.g., 02:00 AM local time).
  • Filter/Exclusion: Create a filter to exclude alerts where the parent process is C:\Program Files\CrowdStrike\fsqa.exe or C:\ProgramData\Microsoft\Windows Defender\platform\4.18.xxxxx\mpclient.dll, and the alert timestamp falls within the defined maintenance window (02:00–04:00).

• Scenario: Automated Software Deployment via SCCM

  • Context: The rule fires when Microsoft Endpoint Configuration Manager (MECM/SCCM) pushes application updates to workstations. During the installation phase, the SCCM client (ccmsetup.exe) often spawns temporary processes that match the Armadillo signature while extracting payloads in the C:\Windows\CCMCache directory.
  • Filter/Exclusion: Exclude alerts where the process path contains \Windows\CCMCache\ and the parent process is identified as ccmsetup.exe. Additionally, filter by user context to exclude SYSTEM or NT AUTHORITY\NETWORK SERVICE accounts during deployment windows.

• Scenario: Cloud Backup Agents (Veeam/AWS)

  • Context: Enterprise backup solutions like Veeam Agent for Windows or AWS Backup agents utilize the Armadillo engine to compress and encrypt