Angler Exploit Kit Detection

Hunt Hypothesis

The Angler Exploit Kit Detection identifies potential exploitation attempts by malicious actors leveraging known exploit kit infrastructure to compromise endpoints. SOC teams should proactively hunt for this behavior in Azure Sentinel to detect early-stage attacks and prevent lateral movement within the network.

YARA Rule

rule angler_flash : EK
{
meta:
   author = "Josh Berry"
   date = "2016-06-26"
   description = "Angler Exploit Kit Detection"
   hash0 = "8081397c30b53119716c374dd58fc653"
   sample_filetype = "unknown"
   yaragenerator = "https://github.com/Xen0ph0n/YaraGenerator"
strings:
   $string0 = "(9OOSp"
   $string1 = "r$g@ 0'[A"
   $string2 = ";R-1qTP"
   $string3 = "xwBtR4"
   $string4 = "YbVjxp"
   $string5 = "ddgXkF"
   $string6 = ")n'URF"
   $string7 = "vAzq@W"
   $string8 = "rOkX$6m<"
   $string9 = "@@DB}q "
   $string10 = "TiKV'iV"
   $string11 = "538x;B"
   $string12 = "9pEM{d"
   $string13 = ".SIy/O"
   $string14 = "ER<Gu,"
condition:
   14 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 15 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 Windows Task Scheduler job that runs a script to update system files or clean temporary data, may trigger the rule if the script uses similar network behavior to the Angler Exploit Kit.
  Filter/Exclusion: Exclude processes initiated by the Task Scheduler with a known benign command-line arguments or parent process (svchost.exe or schtasks.exe).

• Scenario: Admin Tool for Patch Management
  Description: An enterprise admin tool like Microsoft System Center Configuration Manager (SCCM) or Puppet may execute payloads that resemble exploit kit behavior during patch deployment.
  Filter/Exclusion: Exclude processes with parent process msiexec.exe or ccmexec.exe and command-line arguments containing known patch management tool identifiers.

• Scenario: Network Monitoring Tool Traffic
  Description: A network monitoring or security tool like Wireshark or Microsoft Network Monitor may generate traffic that mimics exploit kit C2 (Command and Control) behavior during packet capture or analysis.
  Filter/Exclusion: Exclude traffic from processes with known monitoring tool names or parent processes like wireshark.exe or nmbd.exe.

• Scenario: Legitimate Software Update Process
  Description: A legitimate software update process, such as Adobe Acrobat or Java update, may use similar network protocols or behavior to the Angler Exploit Kit during the update process.
  Filter/Exclusion: Exclude traffic from known software vendors (e.g., AdobeUpdate.exe, JavaUpdate.exe) or processes with known update-related command-line arguments.

• Scenario: Internal Red Team Exercise
  Description: During a red team exercise, a simulated exploit or C2 communication may trigger the rule, especially if the exercise uses similar payloads or network patterns as the Angler Exploit Kit.