BlackHole2 Exploit Kit Detection

Hunt Hypothesis

The hypothesis is that the detection identifies potential exploitation attempts by the BlackHole2 Exploit Kit, which is commonly used to deliver malware through compromised websites. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify and mitigate early-stage attacks before they lead to data exfiltration or system compromise.

YARA Rule

rule blackhole2_htm3 : EK
{
meta:
   author = "Josh Berry"
   date = "2016-06-27"
   description = "BlackHole2 Exploit Kit Detection"
   hash0 = "018ef031bc68484587eafeefa66c7082"
   sample_filetype = "js-html"
   yaragenerator = "https://github.com/Xen0ph0n/YaraGenerator"
strings:
   $string0 = "/download.php"
   $string1 = "./files/fdc7aaf4a3 md5 is 3169969e91f5fe5446909bbab6e14d5d"
   $string2 = "321e774d81b2c3ae"
   $string3 = "/files/new00010/554-0002.exe md5 is 8a497cf4ffa8a173a7ac75f0de1f8d8b"
   $string4 = "./files/3fa7bdd7dc md5 is 8a497cf4ffa8a173a7ac75f0de1f8d8b"
   $string5 = "1603256636530120915 md5 is 425ebdfcf03045917d90878d264773d2"
condition:
   3 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 6 string patterns in its detection logic.

• Source Rule

False Positive Guidance

• Scenario: Scheduled System Maintenance Task
  Description: A legitimate system maintenance task, such as a scheduled backup or disk cleanup, uses a tool like wbadmin or vssadmin which may trigger the rule due to similar network behavior.
  Filter/Exclusion: Exclude processes associated with wbadmin, vssadmin, or task scheduler (e.g., svchost.exe with Task Scheduler service).

• Scenario: Admin Access via Remote Desktop (RDP)
  Description: An administrator connects via RDP to perform routine configuration changes, and the RDP session may trigger the rule due to network traffic patterns.
  Filter/Exclusion: Exclude IP addresses or user accounts associated with known admin access (e.g., admin, administrator, or IP ranges used for internal RDP).

• Scenario: Software Update Deployment via Microsoft Endpoint Manager (MEM)
  Description: A legitimate software update deployment using Microsoft Endpoint Manager (MEM) may involve payloads or scripts that resemble exploit kit behavior.
  Filter/Exclusion: Exclude processes or network traffic associated with Microsoft Intune, Configuration Manager, or MEM services (e.g., msiexec.exe, setup.exe from trusted sources).

• Scenario: Network Monitoring Tool Traffic
  Description: A network monitoring or security tool like Wireshark, tcpdump, or Microsoft Network Monitor may generate traffic that matches the rule’s signature.
  Filter/Exclusion: Exclude processes running Wireshark, tcpdump, or Microsoft Network Monitor (e.g., wireshark.exe, tcpdump.exe, or nmtui.exe).

• Scenario: Legitimate Exploit Kit for Penetration Testing
  Description: A red team or security team uses a legitimate exploit kit (e.g., Metasploit, Cobalt