BlackShades

Hunt Hypothesis

This hypothesis posits that adversaries are leveraging the BlackShades remote access trojan to establish persistent footholds within Azure workloads by executing unauthorized command-and-control communications. Proactive hunting is essential in Azure Sentinel to identify early-stage lateral movement and data exfiltration patterns before they escalate into critical incidents, given the rule’s current low severity may cause initial alerts to be overlooked during routine monitoring.

YARA Rule

rule BlackShades_4 : rat
{
	meta:
		description = "BlackShades"
		author = "Jean-Philippe Teissier / @Jipe_"
		date = "2013-01-12"
		filetype = "memory"
		version = "1.0" 

	strings:
		$a = { 42 00 6C 00 61 00 63 00 6B 00 73 00 68 00 61 00 64 00 65 00 73 }
		$b = { 36 00 3C 00 32 00 20 00 32 00 32 00 26 00 31 00 39 00 3E 00 1D 00 17 00 17 00 1C 00 07 00 1B 00 03 00 07 00 28 00 23 00 0C 00 1D 00 10 00 1B 00 12 00 00 00 28 00 37 00 10 00 01 00 06 00 11 00 0B 00 07 00 22 00 11 00 17 00 00 00 1D 00 1B 00 0B 00 2F 00 26 00 01 00 0B }
		$c = { 62 73 73 5F 73 65 72 76 65 72 }
		$d = { 43 4C 49 43 4B 5F 44 45 4C 41 59 00 53 43 4B 5F 49 44 }
		$e = { 6D 6F 64 49 6E 6A 50 45 }
		$apikey = "f45e373429c0def355ed9feff30eff9ca21eec0fafa1e960bea6068f34209439"

	condition:
		any of ($a, $b, $c, $d, $e) or $apikey		
}

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 6 string patterns in its detection logic.

• Source Rule

False Positive Guidance

Here are 4 specific false positive scenarios for the BlackShades detection rule in an enterprise environment, including suggested filters and exclusions:

• Endpoint Management Agent Updates (e.g., Microsoft Endpoint Configuration Manager / SCCM)

  • Scenario: The BlackShades framework often involves legitimate software installation or update processes that modify system binaries. When SCCM pushes a major Windows Update or an application patch to a large fleet of workstations, the detection logic may flag the mass execution of wuauserv.exe or ccmexec.exe as suspicious activity mimicking BlackShades’ initial deployment phase.
  • Filter/Exclusion: Exclude processes originating from the specific SCCM management server IP range and filter events where the parent process is ccmexec.exe with a known digital signature hash published by Microsoft or the internal IT department.

• Scheduled Antivirus Definition Scans (e.g., CrowdStrike Falcon or SentinelOne)

  • Scenario: BlackShades detections often correlate with file system enumeration and network connection establishment. During nightly scheduled scans, EDR agents like CrowdStrike perform deep directory traversals and initiate connections to update servers. This high-volume I/O and network handshake activity can trigger the rule’s logic regarding “anomalous process behavior” or “unusual network lateral movement.”
  • Filter/Exclusion: Create a time-based exclusion window (e.g., 02:00–04:00 UTC) for events generated by CfSvc.exe (CrowdStrike) or S1Service.exe (SentinelOne). Additionally, exclude traffic destined for known vendor update endpoints (e.g., *.crowdstrike.com, *.sentinelone.net).

• Identity and Access Management Provisioning Tasks (e.g., Okta Workflows or Azure AD Connect)

  • Scenario: In environments using