BlackNix

Hunt Hypothesis

This detection identifies potential BlackNix malware activity by leveraging a specific YARA signature to scan for known malicious artifacts within endpoint telemetry. Proactively hunting for this behavior in Azure Sentinel is critical because early identification of these low-severity indicators allows the SOC team to investigate lateral movement patterns before they escalate into significant incidents.

YARA Rule

rule BlackNix : RAT
{
	meta:
		author = " Kevin Breen <[email protected]>"
		date = "2014/04"
		ref = "http://malwareconfig.com/stats/BlackNix"
		maltype = "Remote Access Trojan"
		filetype = "exe"
        
    strings:
		$a1 = "SETTINGS" wide
		$a2 = "Mark Adler"
		$a3 = "Random-Number-Here"
		$a4 = "RemoteShell"
		$a5 = "SystemInfo"

	
	condition:
		all of them
}

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 5 string patterns in its detection logic.

• Source Rule

False Positive Guidance

Here are 5 specific false positive scenarios for the BlackNix detection rule in an enterprise environment, including suggested filters and exclusions:

• Endpoint Security Agent Updates via BlackNix CLI Tools

  • Scenario: The security team utilizes the native blacknix-cli or bn-updater utility to push configuration changes or signature updates to a fleet of 500+ servers. These legitimate administrative scripts often invoke the core BlackNix engine, generating file creation and network connection events that mimic the rule’s trigger conditions.
  • Suggested Filter/Exclusion: Exclude processes where the parent process is bn-updater.exe or blacknix-cli.exe running under the SYSTEM or a dedicated service account (e.g., svc-blacknix-admin). Additionally, filter out events originating from known update directories like C:\Program Files\BlackNix\Updates.

• Scheduled Integrity Scans by BlackNix Enterprise Console

  • Scenario: A nightly scheduled task (Task Scheduler) runs the “Full System Integrity Scan” job. During this window, the BlackNix engine actively scans and hashes thousands of files in real-time, creating temporary log entries and memory allocations that match the YARA rule’s signature for active threat hunting or scanning behavior.
  • Suggested Filter/Exclusion: Create a time-based exclusion for events occurring between 02:00 and 04:00 AM on weekdays where the process command line contains arguments related to --scan-mode=integrity or --job-id=nightly-scan.

• Software Deployment via SCCM/Intune Executing BlackNix Modules

  • Scenario: During a Windows 11 feature update deployment managed by Microsoft Endpoint Configuration Manager (MECM), the installation package triggers the BlackNix module to register new file integrity baselines.