CDCopsII

Hunt Hypothesis

This detection identifies potential malicious activity associated with the CDCopsII signature, which may indicate an adversary leveraging specific code patterns to establish a foothold or execute custom payloads within the environment. Proactively hunting for this behavior in Azure Sentinel is essential to uncover low-severity indicators that could represent early-stage reconnaissance or lateral movement attempts often missed by standard alerting thresholds.

YARA Rule

rule CDCopsII
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 53 60 BD [4] 8D 45 ?? 8D 5D ?? E8 [4] 8D }

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 4 specific false positive scenarios for the CDCopsII detection rule, including specific enterprise contexts and actionable exclusion strategies:

• Scenario: Scheduled Backup Agent Scans

  • Context: Enterprise backup solutions like Veeam Backup & Replication or Commvault frequently scan large directories of operational data. During these scans, the agents often spawn multiple child processes to index file metadata, which can mimic the behavior patterns (e.g., specific API calls or memory injection) that CDCopsII is designed to detect as suspicious command-line operations.
  • Suggested Filter/Exclusion: Create a process exclusion rule targeting the backup agent’s executable paths (e.g., C:\Program Files\Veeam\Backup and Replication Service\vbagent.exe) and its child processes. Alternatively, filter out alerts where the parent process is identified as the specific backup service during standard maintenance windows (e.g., 02:00–04:00).

• Scenario: Endpoint Detection & Response (EDR) Self-Scans

  • Context: Security tools such as CrowdStrike Falcon, Microsoft Defender for Endpoint, or SentinelOne perform continuous real-time monitoring. When these agents update their signature databases or perform on-access scans, they often execute complex command chains involving PowerShell or native Windows utilities (like powershell.exe spawning cmd.exe) that trigger the CDCopsII YARA logic due to high entropy in command lines or specific registry modifications.
  • Suggested Filter/Exclusion: Implement a “Trusted Process” exclusion list within the SIEM or EDR console for known security tool executables (e.g., C:\Program Files\CrowdStrike\fs_qr.exe). Additionally, add a filter to suppress alerts where the command line contains specific keywords unique to the vendor’s update mechanism (e.g.,