BlackHole1 Exploit Kit Detection

Hunt Hypothesis

Adversaries may use BlackHole1 Exploit Kit to deliver malware through compromised websites, leveraging low-severity indicators to evade traditional detection. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify and mitigate potential compromise early in the attack lifecycle.

YARA Rule

rule blackhole1_jar
{
meta:
   author = "Josh Berry"
   date = "2016-06-26"
   description = "BlackHole1 Exploit Kit Detection"
   hash0 = "724acccdcf01cf2323aa095e6ce59cae"
   sample_filetype = "unknown"
   yaragenerator = "https://github.com/Xen0ph0n/YaraGenerator"
strings:
   $string0 = "Created-By: 1.6.0_18 (Sun Microsystems Inc.)"
   $string1 = "workpack/decoder.classmQ]S"
   $string2 = "workpack/decoder.classPK"
   $string3 = "workpack/editor.classPK"
   $string4 = "xmleditor/GUI.classmO"
   $string5 = "xmleditor/GUI.classPK"
   $string6 = "xmleditor/peers.classPK"
   $string7 = "v(SiS]T"
   $string8 = ",R3TiV"
   $string9 = "META-INF/MANIFEST.MFPK"
   $string10 = "xmleditor/PK"
   $string11 = "Z[Og8o"
   $string12 = "workpack/PK"
condition:
   12 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 13 string patterns in its detection logic.

• Source Rule

False Positive Guidance

• Scenario: System update or patching process using WSUS (Windows Server Update Services)
  Filter/Exclusion: Check for process.name containing wuauclt.exe or wsuapp.exe and filter out processes initiated by the Windows Update service (svchost.exe with wuauserv service).

• Scenario: Scheduled backup job using Veeam Backup & Replication
  Filter/Exclusion: Include process.name like veeambackup.exe and check for process.parent.name being schtasks.exe or taskhost.exe.

• Scenario: Administrative task using PowerShell to configure system settings
  Filter/Exclusion: Filter processes where process.name is powershell.exe and process.parent.name is services.exe or explorer.exe, and check for known administrative scripts or modules.

• Scenario: Log collection or monitoring tool like Splunk Universal Forwarder
  Filter/Exclusion: Include process.name like splunkforwarder.exe and check for process.parent.name being services.exe or splunkd.exe.

• Scenario: Internal network discovery or inventory tool like Nmap or Masscan
  Filter/Exclusion: Filter processes where process.name is nmap.exe or masscan.exe and ensure they are running from a known internal IP range or authorized system.