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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: 2026-06-11T23:00:00Z · Confidence: medium

Hunt Hypothesis

The hypothesis is that the detection of EquationGroup Tool - April Leak indicates potential adversary use of advanced persistent threat techniques to exfiltrate data or establish persistence within the network. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify and mitigate early-stage compromise by sophisticated adversaries leveraging known malware artifacts.

YARA Rule

rule EquationGroup_Toolset_Apr17__DoubleFeatureReader_DoubleFeatureReader_0 {
   meta:
      description = "Detects EquationGroup Tool - April Leak"
      author = "Florian Roth"
      reference = "https://steemit.com/shadowbrokers/@theshadowbrokers/lost-in-translation"
      date = "2017-04-15"
      super_rule = 1
      hash1 = "052e778c26120c683ee2d9f93677d9217e9d6c61ffc0ab19202314ab865e3927"
      hash2 = "5db457e7c7dba80383b1df0c86e94dc6859d45e1d188c576f2ba5edee139d9ae"
   strings:
      $x1 = "DFReader.exe logfile AESKey [-j] [-o outputfilename]" fullword ascii
      $x2 = "Double Feature Target Version" fullword ascii
      $x3 = "DoubleFeature Process ID" fullword ascii

      $op1 = { a1 30 21 41 00 89 85 d8 fc ff ff a1 34 21 41 00 }
   condition:
      ( uint16(0) == 0x5a4d and filesize < 300KB and 1 of them ) or ( 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