Obsidium1337ObsidiumSoftware

Hunt Hypothesis

This YARA rule targets the Obsidium1337ObsidiumSoftware signature, indicating the presence of a specific low-severity software component or potential backdoor that adversaries may deploy to establish a foothold or execute malicious logic. Proactively hunting for this signature in Azure Sentinel allows the SOC team to identify and isolate hosts running this known artifact before it can be leveraged for lateral movement or data exfiltration.

YARA Rule

rule Obsidium1337ObsidiumSoftware
{
      meta:
		author="malware-lu"
strings:
		$a0 = { EB 02 [2] E8 2C 00 00 00 EB 04 [4] EB 04 [4] 8B 54 24 0C EB 02 [2] 83 82 B8 00 00 00 27 EB 04 [4] 33 C0 EB 02 [2] C3 EB 02 [2] EB 03 [3] 64 67 FF 36 00 00 EB 04 [4] 64 67 89 26 00 00 EB 03 [3] EB 01 ?? 50 EB 02 [2] 33 C0 EB 02 [2] 8B 00 EB 04 [4] C3 EB 02 [2] E9 FA 00 00 00 EB 04 [4] E8 D5 FF FF FF EB 02 [2] EB 04 [4] 58 EB 04 [4] EB 03 [3] 64 67 8F 06 00 00 EB 01 ?? 83 C4 04 EB 03 [3] E8 23 27 00 00 }

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

• Legacy .NET Application Deployment: The rule likely targets specific byte patterns or strings associated with Obsidium software (often used for digital rights management or specific enterprise licensing). This can trigger on legitimate installations of older .NET-based line-of-business applications that embed Obsidium licensing components.
  • Filter/Exclusion: Exclude known application directories such as C:\Program Files\Obsidium\ or specific legacy app paths like C:\Program Files (x86)\[LegacyApp]\bin\.
• Scheduled License Renewal Jobs: Many enterprises use scheduled tasks to automatically renew software licenses or validate DRM keys, which may involve executing Obsidium-related executables or DLLs.
  • Filter/Exclusion: Exclude processes spawned by Task Scheduler (svchost.exe with specific arguments) or specific service names like ObsidiumLicenseService if it is a registered Windows service.
• Antivirus/EDR Quarantine Scans: Security tools often scan or interact with known software binaries during full system scans. If the YARA rule matches the binary header or specific code sections, it may trigger during active scanning operations by tools like Microsoft Defender, CrowdStrike, or SentinelOne.
  • Filter/Exclusion: Exclude processes from known security vendors, e.g., MsMpEng.exe (Defender), CrowdStrike Falcon, or SentinelOne Agent, when the parent process is a security tool.
• Development and Testing Environments: Developers or QA engineers may run Obsidium-protected applications or test builds in development environments, especially if they are using virtual machines or containerized environments for testing.
  • Filter/Exclusion: Exclude hosts tagged with dev, test, or qa in CMDB or AD groups, or exclude paths under C:\Users\[DevUser]\Projects\ or `C:\Temp\