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YARA · Signature Base (Florian Roth / Nextron)

SIGNATURE_BASE_HKTL_Cobaltstrike_Beacon_4_2_Decrypt

Identifies deobfuscation routine used in Cobalt Strike Beacon DLL version 4.2

Hack toolCobalt StrikeSignature Base (Florian Roth / Nextron)Detection Rule License 1.1Compiles with YARA-X
Author
Elastic
Date
2021-03-16
Modified
2026-05-26
Score / Quality
75 / 85

What this rule detects

Identifies deobfuscation routine used in Cobalt Strike Beacon DLL version 4.2

Associated malware family: Cobalt Strike.

It defines 2 patterns (0 text, 2 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

Download .yar
hktl-cobaltstrike-beacon-4-2-decrypt.yarDetection Rule License 1.1
rule SIGNATURE_BASE_HKTL_Cobaltstrike_Beacon_4_2_Decrypt
{
	meta:
		description = "Identifies deobfuscation routine used in Cobalt Strike Beacon DLL version 4.2"
		author = "Elastic"
		id = "63b71eef-0af5-5765-b957-ccdc9dde053b"
		date = "2021-03-16"
		modified = "2026-05-26"
		reference = "https://www.elastic.co/blog/detecting-cobalt-strike-with-memory-signatures"
		source_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/apt_cobaltstrike.yar#L92-L104"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		logic_hash = "8685b1626c8d263f49ccf129dcd4fe1b42482fcdb37c2e109cedcecaed8c2407"
		score = 75
		quality = 85
		tags = ""

	strings:
		$a_x64 = { 4C 8B 53 08 45 8B 0A 45 8B 5A 04 4D 8D 52 08 45 85 C9 75 05 45 85 DB 74 33 45 3B CB 73 E6 49 8B F9 4C 8B 03 }
		$a_x86 = { 8B 46 04 8B 08 8B 50 04 83 C0 08 89 55 08 89 45 0C 85 C9 75 04 85 D2 74 23 3B CA 73 E6 8B 06 8D 3C 08 33 D2 }

	condition:
		any of them
}

Strings (2 patterns)

IdentifierTypeValueModifiers
$a_x64hex{ 4C 8B 53 08 45 8B 0A 45 8B 5A 04 4D 8D 52 08 45 85 C9 75 05 45 85 DB 74 33 45 3B CB 73 E6 49 8B F9 4C 8B 03 }
$a_x86hex{ 8B 46 04 8B 08 8B 50 04 83 C0 08 89 55 08 89 45 0C 85 C9 75 04 85 D2 74 23 3B CA 73 E6 8B 06 8D 3C 08 33 D2 }

Condition

any of them

In plain words (Heuristic)

  • At least one pattern in the rule must match.

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References

Licence & attribution

Author: Elastic

Source repository: Signature Base (Florian Roth / Nextron) @ 94a1c48d7a

Licence: Detection Rule License 1.1 (repository licence)

Original rule

Mirrored via YARA Forge 20260927, which prefixes rule names with the source and adds normalised meta fields.

Rule id: 63b71eef-0af5-5765-b957-ccdc9dde053b

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