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Equation Group Malware - Grey Fish

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: 2026-05-23T11:00:00Z · Confidence: medium

Hunt Hypothesis

The hunt hypothesis detects potential Equation Group malware activity associated with the Grey Fish variant, which may indicate advanced persistent threat (APT) behavior. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify and mitigate early-stage adversarial activity that could lead to data exfiltration or system compromise.

YARA Rule

rule Equation_Kaspersky_GreyFishInstaller
{

    meta:
        description = "Equation Group Malware - Grey Fish"
        author = "Florian Roth"
        reference = "http://goo.gl/ivt8EW"
        date = "2015/02/16"
        hash = "58d15d1581f32f36542f3e9fb4b1fc84d2a6ba35"

    strings:
        $s0 = "DOGROUND.exe" fullword wide
        $s1 = "Windows Configuration Services" fullword wide
        $s2 = "GetMappedFilenameW" fullword ascii

    condition:
        all of them
}

Deployment Notes

This YARA rule can be deployed in the following contexts:

This rule contains 3 string patterns in its detection logic.

References

False Positive Guidance

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