Equation Group hack tool set

Hunt Hypothesis

The Equation Group hack tool set is likely used by advanced adversaries to establish persistence and exfiltrate data within a network. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify potential long-term compromise and mitigate the risk of data theft or lateral movement.

YARA Rule

rule EquationGroup_curseroot_win2k_v_2_1_0 {
   meta:
      description = "Equation Group hack tool set"
      author = "Florian Roth"
      reference = "https://medium.com/@shadowbrokerss/dont-forget-your-base-867d304a94b1"
      date = "2017-04-09"
      hash1 = "a1637948ed6ebbd2e582eb99df0c06b27a77c01ad1779b3d84c65953ca2cb603"
   strings:
      $s1 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/%s,%s" fullword ascii
      $op0 = { c7 44 24 04 ff ff ff ff 89 04 24 e8 46 65 01 00 } /* Opcode */
      $op1 = { 8d 5d 88 89 1c 24 e8 24 1b 01 00 be ff ff ff ff } /* Opcode */
      $op2 = { d3 e0 48 e9 0c ff ff ff 8b 45 } /* Opcode */
   condition:
      ( uint16(0) == 0x5a4d and filesize < 400KB and $s1 and 2 of ($op*) )
}

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 4 string patterns in its detection logic.

References

• https://medium.com/@shadowbrokerss/dont-forget-your-base-867d304a94b1
• Source Rule

False Positive Guidance

• Scenario: Legitimate System Maintenance Task
  Description: A system administrator is running a scheduled maintenance job that uses the Equation Group tool (e.g., eqgrp.exe) to clean up temporary files or perform disk defragmentation.
  Filter/Exclusion: Exclude processes initiated by scheduled tasks with known maintenance scripts or by the local system account.

• Scenario: Security Software Update
  Description: A security tool or endpoint protection software (e.g., Microsoft Defender, CrowdStrike) is using a tool with a similar name to the Equation Group tool as part of an update or integrity check.
  Filter/Exclusion: Exclude processes from known security vendors or those running under the Windows Defender or Microsoft Antimalware service.

• Scenario: Network Monitoring Tool Usage
  Description: A network monitoring or packet capture tool (e.g., Wireshark, tcpdump) is using a tool with a similar name to the Equation Group tool for packet analysis or logging.
  Filter/Exclusion: Exclude processes associated with network analysis tools or running under the NetworkService account.

• Scenario: Legacy Software Compatibility Check
  Description: A legacy application or compatibility tool is using a tool with a similar name to the Equation Group tool to check for system compatibility or run diagnostics.
  Filter/Exclusion: Exclude processes from known legacy software vendors or those running under a non-administrative user account.

• Scenario: Custom Script or Automation Tool
  Description: A custom script or automation tool (e.g., PowerShell, Python) is using a tool with a similar name to the Equation Group tool for system configuration or deployment.
  Filter/Exclusion: Exclude processes initiated by user scripts or those running under a non-administrative user account with no known malicious intent.