Skip to content
yararules.org
Menu

YARA · Signature Base (Florian Roth / Nextron)

SIGNATURE_BASE_MAL_Cobaltstrike_Beacon_Loader_Feb26

Detects Cobalt Strike beacon loader

MalwareCobalt StrikeSignature Base (Florian Roth / Nextron)Detection Rule License 1.1Compiles with YARA-X
Author
X__Junior
Date
2026-02-02
Modified
2026-05-15
Score / Quality
80 / 85

What this rule detects

Detects Cobalt Strike beacon loader

Associated malware family: Cobalt Strike.

Targets: Windows PE.

It defines 4 patterns (0 text, 4 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

Download .yar
mal-cobaltstrike-beacon-loader-feb26.yarDetection Rule License 1.1
rule SIGNATURE_BASE_MAL_Cobaltstrike_Beacon_Loader_Feb26 : FILE
{
	meta:
		description = "Detects Cobalt Strike beacon loader"
		author = "X__Junior"
		id = "9d6888d0-64c6-5e52-a01a-8bcc51dd16b1"
		date = "2026-02-02"
		modified = "2026-05-15"
		reference = "https://www.rapid7.com/blog/post/tr-chrysalis-backdoor-dive-into-lotus-blossoms-toolkit/"
		source_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/lotusblossom_notepad_exploitation.yar#L53-L73"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		hash = "0a9b8df968df41920b6ff07785cbfebe8bda29e6b512c94a3b2a83d10014d2fd"
		hash = "b4169a831292e245ebdffedd5820584d73b129411546e7d3eccf4663d5fc5be3"
		logic_hash = "949e70b1fb7f270a05d1626a12595ecab22bdec37a07e83c5cf64399506302a5"
		score = 80
		quality = 85
		tags = "FILE"

	strings:
		$opa1 = { 45 33 C9 41 B8 ?? ?? ?? ?? 48 8D 94 24 ?? ?? ?? ?? 48 8D 4C 24 ?? E8 ?? ?? ?? ?? 48 8D 8C 24 ?? ?? ?? ?? FF 15 ?? ?? ?? ?? 66 89 44 24 ?? 41 B8 ?? ?? ?? ?? 48 8D 94 24 ?? ?? ?? ?? 0F B7 4C 24 ?? FF 15 ?? ?? ?? ?? 48 8D 8C 24 ?? ?? ?? ?? FF 15 }
		$opa2 = { 4C 8D 4C 24 ?? 41 B8 ?? ?? ?? ?? BA ?? ?? ?? ?? 48 8D 8C 24 ?? ?? ?? ?? FF 15 ?? ?? ?? ?? FF 15 ?? ?? ?? ?? 48 C7 44 24 ?? ?? ?? ?? ?? C7 44 24 ?? ?? ?? ?? ?? 48 8D 8C 24 ?? ?? ?? ?? 48 89 4C 24 ?? 4C 8D 0D ?? ?? ?? ?? 45 33 C0 33 D2 48 8B C8 FF 15 }
		$opb1 = { 48 8D 89 ?? ?? ?? ?? 0F 10 00 0F 10 48 ?? 48 8D 80 ?? ?? ?? ?? 0F 11 41 ?? 0F 10 40 ?? 0F 11 49 ?? 0F 10 48 ?? 0F 11 41 ?? 0F 10 40 ?? 0F 11 49 ?? 0F 10 48 ?? 0F 11 41 ?? 0F 10 40 ?? 0F 11 49 ?? 0F 10 48 ?? 0F 11 41 ?? 0F 11 49 ?? 48 83 EA }
		$opb2 = { 45 33 C9 48 89 84 24 ?? ?? ?? ?? 41 B8 18 00 00 00 C7 84 24 ?? ?? ?? ?? 03 00 00 00 48 8D 94 24 ?? ?? ?? ?? 48 89 BC 24 ?? ?? ?? ?? B9 B9 00 00 00 FF 15 }

	condition:
		uint16( 0 ) == 0x5a4d and all of ( $opa* ) or all of ( $opb* )
}

Strings (4 patterns)

IdentifierTypeValueModifiers
$opa1hex{ 45 33 C9 41 B8 ?? ?? ?? ?? 48 8D 94 24 ?? ?? ?? ?? 48 8D 4C 24 ?? E8 ?? ?? ?? ?? 48 8D 8C 24 ?? ?? ?? ?? FF 15 ?? ?? ?? ?? 66 89 44 24 ?? 41 B8 ?? ?? ?? ?? 48 …
$opa2hex{ 4C 8D 4C 24 ?? 41 B8 ?? ?? ?? ?? BA ?? ?? ?? ?? 48 8D 8C 24 ?? ?? ?? ?? FF 15 ?? ?? ?? ?? FF 15 ?? ?? ?? ?? 48 C7 44 24 ?? ?? ?? ?? ?? C7 44 24 ?? ?? ?? ?? ?? …
$opb1hex{ 48 8D 89 ?? ?? ?? ?? 0F 10 00 0F 10 48 ?? 48 8D 80 ?? ?? ?? ?? 0F 11 41 ?? 0F 10 40 ?? 0F 11 49 ?? 0F 10 48 ?? 0F 11 41 ?? 0F 10 40 ?? 0F 11 49 ?? 0F 10 48 ?? …
$opb2hex{ 45 33 C9 48 89 84 24 ?? ?? ?? ?? 41 B8 18 00 00 00 C7 84 24 ?? ?? ?? ?? 03 00 00 00 48 8D 94 24 ?? ?? ?? ?? 48 89 BC 24 ?? ?? ?? ?? B9 B9 00 00 00 FF 15 }

Condition

uint16( 0 ) == 0x5a4d and all of ( $opa* ) or all of ( $opb* )

In plain words (Heuristic)

  • The file must start with “MZ” — a Windows executable (PE).
  • All patterns in ( $opa* ) must match.
  • All patterns in ( $opb* ) must match.

Test this rule in your browser

Drop a file to scan it with this rule using YARA-X compiled to WebAssembly. Nothing is uploaded.

Drop a file here or click to chooseScanned locally with YARA-X. Files up to 200 MB.

Open in editor

References

Sample hashes

Hashes of samples the author lists in the rule's meta (look them up in your threat-intelligence platform).

  • 0a9b8df968df41920b6ff07785cbfebe8bda29e6b512c94a3b2a83d10014d2fd
  • b4169a831292e245ebdffedd5820584d73b129411546e7d3eccf4663d5fc5be3

Licence & attribution

Author: X__Junior

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: 9d6888d0-64c6-5e52-a01a-8bcc51dd16b1

Tags:FILE

Related rules

More Cobalt Strike rules