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Detects EquationGroup Tool - April Leak

yara LOW Yara-Rules
community
This rule was pulled from an open-source repository and enriched with AI. Validate in a test environment before deploying to production.
View original rule at Yara-Rules →
Retrieved: 2026-06-09T23:00:00Z · Confidence: medium

Hunt Hypothesis

The detection identifies potential use of the EquationGroup tool, specifically the April Leak variant, which may indicate advanced persistent threat activity. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify and mitigate early-stage adversary presence and potential data exfiltration.

YARA Rule

rule EquationGroup_Toolset_Apr17_ntevt {
   meta:
      description = "Detects EquationGroup Tool - April Leak"
      author = "Florian Roth"
      reference = "https://steemit.com/shadowbrokers/@theshadowbrokers/lost-in-translation"
      date = "2017-04-15"
      hash1 = "4254ee5e688fc09bdc72bcc9c51b1524a2bb25a9fb841feaf03bc7ec1a9975bf"
   strings:
      $x1 = "c:\\ntevt.pdb" fullword ascii

      $s1 = "ARASPVU" fullword ascii

      $op1 = { 41 5a 41 59 41 58 5f 5e 5d 5a 59 5b 58 48 83 c4 }
      $op2 = { f9 48 03 fa 48 33 c0 8a 01 49 03 c1 49 f7 e0 88 }
      $op3 = { 01 41 f6 e0 49 03 c1 88 01 48 33 }
   condition:
      ( uint16(0) == 0x5a4d and filesize < 700KB and $x1 or 3 of them )
}

Deployment Notes

This YARA rule can be deployed in the following contexts:

This rule contains 5 string patterns in its detection logic.

References

False Positive Guidance

Original source: https://github.com/Yara-Rules/rules/blob/main/malware/APT_eqgrp_apr17.yar