9002 code features

Hunt Hypothesis

The detection rule identifies potential code obfuscation or suspicious code features that may indicate adversarial activity attempting to evade standard detection mechanisms. SOC teams should proactively hunt for this behavior in Azure Sentinel to uncover stealthy, low-and-slow attacks that may bypass traditional security controls.

YARA Rule

rule APT9002Code 
{
    
    meta:
        description = "9002 code features"
        author = "Seth Hardy"
        last_modified = "2014-06-25"
        
    strings:
        // start code block
        $ = { B9 7A 21 00 00 BE ?? ?? ?? ?? 8B F8 ?? ?? ?? F3 A5 }
        // decryption from other variant with multiple start threads
        $ = { 8A 14 3E 8A 1C 01 32 DA 88 1C 01 8B 54 3E 04 40 3B C2 72 EC }

    condition:
        any 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
• Source Rule

False Positive Guidance

• Scenario: A system administrator is using PowerShell to automate the deployment of a new application that includes a 9002 code feature.
  Filter/Exclusion: Check for the presence of PowerShell scripts in known admin directories (e.g., C:\Windows\System32\WindowsPowerShell\v1.0\) and exclude events originating from scheduled tasks or admin scripts.

• Scenario: A scheduled job runs nightly to update a legacy application that uses 9002 code features for compatibility.
  Filter/Exclusion: Exclude events that occur during scheduled maintenance windows (e.g., between 1:00 AM and 3:00 AM) or filter by the job name (e.g., UpdateLegacyApp).

• Scenario: A developer is testing a new feature in a development environment using Visual Studio and the 9002 code feature is part of the test case.
  Filter/Exclusion: Filter by source IP or user account (e.g., dev-user) and exclude activity from development machines (e.g., 192.168.1.100).

• Scenario: A system update or patching process includes a 9002 code feature as part of a Windows Update or Microsoft Intune deployment.
  Filter/Exclusion: Exclude events related to Windows Update or Intune by checking the event source (e.g., Microsoft-Windows-WindowsUpdate) or the update package name.

• Scenario: A third-party tool like Sysinternals Process Explorer or Wireshark is used to analyze network traffic that includes 9002 code features for diagnostic purposes.
  Filter/Exclusion: Exclude events associated with known diagnostic tools by checking the process name or user context (e.g., ProcessExplorer.exe, wireshark.exe).