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Codoso CustomTCP Malware

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: 2026-05-20T23:00:01Z · Confidence: medium

Hunt Hypothesis

The Codoso CustomTCP Malware is likely establishing covert communication channels over custom TCP ports to exfiltrate data and maintain persistence. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify and mitigate potential long-term adversary presence and data leakage.

YARA Rule

rule Codoso_CustomTCP
{

    meta:
        description = "Codoso CustomTCP Malware"
        author = "Florian Roth"
        reference = "https://www.proofpoint.com/us/exploring-bergard-old-malware-new-tricks"
        date = "2016-01-30"
        hash = "b95d7f56a686a05398198d317c805924c36f3abacbb1b9e3f590ec0d59f845d8"

    strings:
        $s4 = "wnyglw" fullword ascii
        $s5 = "WorkerRun" fullword ascii
        $s7 = "boazdcd" fullword ascii
        $s8 = "wayflw" fullword ascii
        $s9 = "CODETABL" fullword ascii

    condition:
        uint16(0) == 0x5a4d and filesize < 405KB and all of them
}

Deployment Notes

This YARA rule can be deployed in the following contexts:

This rule contains 5 string patterns in its detection logic.

References

False Positive Guidance

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