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apt_malware_win_early_govershell_variant

YARA detection rule by threatintel@volexity.com · See license at https://github.com/volexity/threat-intel/blob/main/LICENSE.txt

This rule detects an early variant of the GOVERSHELL malware family employed by UTA0388 in H1 2025. The malware family overlaps with the Golang GOVERSHELL implants used by UTA0388 in terms of design and infrastructure, but is not written in Golang. The implants are peDLLs that are side-loaded by a legitimate executable file.

rule apt_malware_win_early_govershell_variant: UTA0388
{
    meta:
        author = "threatintel@volexity.com"
        date = "2025-06-30"
        description = "This rule detects an early variant of the GOVERSHELL malware family employed by UTA0388 in H1 2025. The malware family overlaps with the Golang GOVERSHELL implants used by UTA0388 in terms of design and infrastructure, but is not written in Golang. The implants are peDLLs that are side-loaded by a legitimate executable file."
        hash1 = "4ee77f1261bb3ad1d9d7114474a8809929f4a0e7f9672b19048e1b6ac7acb15c"
        hash2 = "9b2cbcf2e0124d79130c4049f7b502246510ab681a3a84224b78613ef322bc79"
        os = "win"
        os_arch = "all"
        scan_context = "file"
        severity = "critical"
        last_modified = "2025-10-08T09:21:38Z"
        license = "See license at https://github.com/volexity/threat-intel/blob/main/LICENSE.txt"
        rule_id = 11994
        version = 6

    strings:
        $a1 = "cmd.exe /c %s"
        $a2 = "randomDir"
        $a3 = "C:\\ProgramData\\"
        $a4 = "*.dll"
        $a5 = ".\\%s"
        $a6 = "%s\\%s"
        $a7 = "SystemHealthMonitor"
        $a8 = "C:\\ProgramData\\%s"
        $a9 = "mysecretkey"
        $a10 = "destExe"
        $a11 = "selfPath"
        $a12 = "srcPath"
        $a13 = "findData"
        $a14 = "exitCode"
        $a15 = "exePathW"
        $a16 = "cmdSize"
        $a17 = "httpsSize"
        $a18 = "newExePathW"
        $a19 = "currentExePath"

    condition:
        uint16be(0) == 0x4D5A and
        8 of ($a*)
}

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

33e5d28e-4511-4bec-8cf6-1ff3ae924791

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Executable code, not a declarative rule

This submission is arbitrary [[ currentRule.format ? currentRule.format.toUpperCase() : '' ]] code, not a declarative detection rule — review it as you would any script before running it, and note that it cannot be safely aggregated or auto-executed alongside YARA/Sigma/Suricata/CRS rules.

Rejected pattern present

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Format & documentation suggestions

Not a security issue — this rule is valid and was accepted as-is. These are optional fields/conventions its own format recommends, mainly affecting its quality score and how well it documents itself for other reviewers.

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