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Detects EquationGroup Tool - April Leak

yara LOW Yara-Rules
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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: 2026-06-10T11:00:00Z · Confidence: medium

Hunt Hypothesis

The hypothesis is that the detection of the EquationGroup Tool - April Leak indicates potential adversary activity leveraging a known malware variant associated with advanced persistent threats. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify and mitigate early-stage compromises that may evade traditional detection methods.

YARA Rule

rule EquationGroup_Toolset_Apr17_GenKey {
   meta:
      description = "Detects EquationGroup Tool - April Leak"
      author = "Florian Roth"
      reference = "https://steemit.com/shadowbrokers/@theshadowbrokers/lost-in-translation"
      date = "2017-04-15"
      hash1 = "b6f100b21da4f7e3927b03b8b5f0c595703b769d5698c835972ca0c81699ff71"
   strings:
      $x1 = "* PrivateEncrypt -> PublicDecrypt FAILED" fullword ascii
   condition:
      ( uint16(0) == 0x5a4d and filesize < 80KB and all of them )
}

Deployment Notes

This YARA rule can be deployed in the following contexts:

This rule contains 1 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