Windows_Trojan_CobaltStrike_1787eef5

YARA detection rule by Elastic Security · Elastic License v2

CS shellcode variants

rule Windows_Trojan_CobaltStrike_1787eef5 {
    meta:
        author = "Elastic Security"
        id = "1787eef5-ff00-4e19-bd22-c5dfc9488c7b"
        fingerprint = "801e88bae61c0d9df0da595d37fbd194c4d9985bdaf787724d553fa9fe8c4740"
        creation_date = "2022-08-29"
        last_modified = "2025-06-11"
        description = "CS shellcode variants"
        threat_name = "Windows.Trojan.CobaltStrike"
        reference_sample = "36d32b1ed967f07a4bd19f5e671294d5359009c04835601f2cc40fb8b54f6a2a"
        severity = 100
        arch_context = "x86, arm64"
        scan_context = "file, memory"
        license = "Elastic License v2"
        os = "windows"
    strings:
        $a1 = { 55 89 E5 83 EC 18 A1 ?? ?? ?? 00 C7 04 24 ?? ?? ?? ?? 89 44 24 04 E8 ?? ?? FF FF 31 C0 C9 C3 55 }
        $a2 = { 55 89 E5 83 EC ?? A1 ?? ?? ?? ?? 89 04 24 E8 ?? ?? ?? ?? 31 C0 C9 C3 55 89 E5 83 EC ?? 83 7D ?? ?? }
        $a3 = { 55 89 E5 8B 45 ?? 5D FF E0 55 8B 15 ?? ?? ?? ?? 89 E5 8B 45 ?? 85 D2 7E ?? 83 3D ?? ?? ?? ?? ?? }
        $a4 = { 55 89 E5 8B 45 ?? 5D FF E0 55 89 E5 83 EC ?? 8B 15 ?? ?? ?? ?? 8B 45 ?? 85 D2 7E ?? 83 3D ?? ?? ?? ?? ?? }
        $a5 = { 4D 5A 41 52 55 48 89 E5 48 81 EC ?? ?? ?? ?? 48 8D 1D ?? ?? ?? ?? 48 89 DF 48 81 C3 ?? ?? ?? ?? }
    condition:
        1 of ($a*)
}

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

2e11574f-8e37-4a2e-aad9-01dc0fb6f220

Propose edits, view related rules, and engage with the community through comments.

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

[[ reason ]]

What does this mean?

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.

[[ reason ]]

What do these messages mean?

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

[[ currentRule.title ]]

Community Discussion