Equation Group hack tool leaked by ShadowBrokers- file ebbisland

Hunt Hypothesis

The detection identifies potential exploitation of the Equation Group hack tool, ebbisland, which may indicate unauthorized access or lateral movement within a network. SOC teams should proactively hunt for this behavior to identify and mitigate potential advanced persistent threats leveraging leaked malware in their Azure Sentinel environment.

YARA Rule

rule EquationGroup_ebbisland {
   meta:
      description = "Equation Group hack tool leaked by ShadowBrokers- file ebbisland"
      author = "Florian Roth"
      reference = "https://medium.com/@shadowbrokerss/dont-forget-your-base-867d304a94b1"
      date = "2017-04-08"
      hash1 = "eba07c98c7e960bb6c71dafde85f5da9f74fd61bc87793c87e04b1ae2d77e977"
   strings:
      $x1 = "Usage: %s [-V] -t <target_ip> -p port" fullword ascii
      $x2 = "error - shellcode not as expected - unable to fix up" fullword ascii
      $x3 = "WARNING - core wipe mode - this will leave a core file on target" fullword ascii
      $x4 = "[-C] wipe target core file (leaves less incriminating core on failed target)" fullword ascii
      $x5 = "-A <jumpAddr> (shellcode address)" fullword ascii
      $x6 = "*** Insane undocumented incremental port mode!!! ***" fullword ascii
   condition:
      filesize < 250KB and 1 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.

References

False Positive Guidance

Scenario: Legitimate System File Access
Description: A system administrator accesses the ebbisland file as part of routine maintenance or forensic analysis.
Filter/Exclusion: Check for process.owner containing “admin” or “root” and filter out processes with process.name like explorer.exe, taskmgr.exe, or regedit.exe.
Scenario: Scheduled Job Execution
Description: A scheduled task or service runs a script that interacts with the ebbisland file as part of a legitimate configuration or update process.
Filter/Exclusion: Filter out events where process.parent.name is a known service or task scheduler process (e.g., svchost.exe, taskhostw.exe) and check for process.command_line containing known legitimate command-line arguments.
Scenario: Antivirus or EDR Tool Scanning
Description: An endpoint detection and response (EDR) tool or antivirus software scans the ebbisland file during a routine integrity check or malware scan.
Filter/Exclusion: Filter out processes where process.name is a known EDR or antivirus tool (e.g., mpsvc.exe, msseces.exe, mcafee.exe) and check for process.parent.name matching these tools.
Scenario: File Integrity Monitoring (FIM) Alert
Description: A file integrity monitoring tool flags changes to the ebbisland file, which is part of a legitimate system configuration or log file.
Filter/Exclusion: Filter out events where file.path matches known FIM-monitored files and check for file.hash matching known legitimate hashes.
Scenario: Developer or DevOps Tool Usage
Description: A developer or DevOps engineer uses a tool like PowerShell, Python, or