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Rule to detect the Corkow DLL files

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: 2026-06-13T23:00:00Z · Confidence: medium

Hunt Hypothesis

The Corkow DLL files are indicative of potential adversary activity, as they are often used in malware deployment and persistence mechanisms. SOC teams should proactively hunt for these files in Azure Sentinel to identify and mitigate early-stage threats before they escalate.

YARA Rule

rule CorkowDLL
{

    meta:
        description = "Rule to detect the Corkow DLL files"
        reference = "IB-Group | http://www.group-ib.ru/brochures/Group-IB-Corkow-Report-EN.pdf"

    strings:
        $mz = { 4d 5a }
        $binary1 = {60 [0-8] 9C [0-8] BB ?? ?? ?? ?? [0-8] 81 EB ?? ?? ?? ?? [0-8] E8 ?? 00 00 00 [0-8] 58 [0-8] 2B C3}
        $binary2 = {(FF75??|53)FF7510FF750CFF7508E8????????[3-9]C9C20C 00}
        $export1 = "Control_RunDLL"
        $export2 = "ServiceMain"
        $export3 = "DllGetClassObject"

    condition:
        ($mz at 0) and ($binary1 and $binary2) and any of ($export*)
}

Deployment Notes

This YARA rule can be deployed in the following contexts:

This rule contains 6 string patterns in its detection logic.

References

False Positive Guidance

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