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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: 2026-06-09T11:00:00Z · Confidence: medium

Hunt Hypothesis

The hypothesis is that the detection of the EquationGroup Tool - April Leak indicates potential adversary use of a sophisticated, previously disclosed malware variant, which may be part of a targeted attack. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify and mitigate potential compromise from advanced persistent threats leveraging known but dormant malware.

YARA Rule

rule EquationGroup_Toolset_Apr17_yak {
   meta:
      description = "Detects EquationGroup Tool - April Leak"
      author = "Florian Roth"
      reference = "https://steemit.com/shadowbrokers/@theshadowbrokers/lost-in-translation"
      date = "2017-04-15"
      hash1 = "66ff332f84690642f4e05891a15bf0c9783be2a64edb2ef2d04c9205b47deb19"
   strings:
      $x1 = "-xd = dump archive data & store in scancodes.txt" fullword ascii
      $x2 = "-------- driver start token -------" fullword wide
      $x3 = "-------- keystart token -------" fullword wide
      $x4 = "-xta = same as -xt but show special chars & store in keys_all.txt" fullword ascii
   condition:
      ( uint16(0) == 0x5a4d and filesize < 800KB and 2 of them )
}

Deployment Notes

This YARA rule can be deployed in the following contexts:

This rule contains 4 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