ORiENv211212FisunAlexander

Hunt Hypothesis

This YARA rule targets specific file patterns associated with the ORiENv211212FisunAlexander signature, indicating the presence of a low-severity threat artifact or known malicious component within the environment. Proactively hunting for this signature allows the SOC team to identify dormant or low-impact intrusions early, ensuring that potentially overlooked footholds are remediated before they can be leveraged for lateral movement or privilege escalation.

YARA Rule

rule ORiENv211212FisunAlexander
{
      meta:
		author="malware-lu"
strings:
		$a0 = { E9 5D 01 00 00 CE D1 CE ?? 0D 0A 2D 2D 2D 2D 2D 2D 2D 2D 2D 2D 2D 2D 2D 2D 2D 2D 2D 2D 2D 2D 2D 2D 2D 2D 2D 2D 2D 2D 2D 2D 2D 2D 2D 2D 2D 2D 2D 2D 2D 2D 2D 2D 2D 2D 0D 0A 2D 20 4F 52 69 45 4E 20 65 78 65 63 75 74 61 62 6C 65 20 66 69 6C 65 73 20 70 72 6F }

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

• Scenario: A DevOps engineer uses kubectl or helm to deploy a new microservice that includes a custom init container or sidecar written in Go or Rust, which embeds a static binary or shared library matching the YARA signature.
  • Filter/Exclusion: Exclude files located in /usr/local/bin/, /opt/app/bin/, or within Kubernetes pod volumes mounted from ConfigMaps or Secrets where the parent process is kubectl, helm, or containerd-shim.
• Scenario: An IT administrator runs a scheduled PowerShell script (C:\Scripts\UpdateDrivers.ps1) that downloads and executes a vendor-provided installer (e.g., NVIDIA, Intel, or Logitech) from a trusted internal repository, where the installer’s temporary extraction folder contains a binary matching the rule.
  • Filter/Exclusion: Exclude processes where the parent process is powershell.exe or pwsh.exe and the file path contains \Temp\ or \Downloads\ with a hash match against a known-good vendor installer baseline, or exclude if the parent process is msiexec.exe and the source is an internal share (\\fileserver\apps\).
• Scenario: A security team runs a YARA scan or AV update cycle using a tool like clamscan or VirusTotal Updater that temporarily loads or extracts signature databases or helper binaries into a working directory, triggering the rule on the helper executable.
  • Filter/Exclusion: Exclude files in directories named yara, clamav, or vt-updater where the parent process is clamscan.exe, yara.exe, or vt-updater.exe, and the file extension is .exe or .so with a size < 5MB.
• Scenario: A Java or .NET application