YARA · SEKOIA.IO Community

SEKOIA_Bot_Win_Yamabot

Detect the Yamabot implant used by Lazarus

APT / threat actorSEKOIA.IO CommunityDetection Rule License 1.1Compiles with YARA-X

Author: Sekoia.io
Date: 2023-08-29
Modified: 2024-12-19
Score / Quality: 75 / 80

What this rule detects

Detect the Yamabot implant used by Lazarus

Targets: Windows PE.

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

Summary generated from the rule's metadata and condition.

Rule source

Download .yar

bot-win-yamabot.yarDetection Rule License 1.1

rule SEKOIA_Bot_Win_Yamabot : FILE
{
	meta:
		description = "Detect the Yamabot implant used by Lazarus"
		author = "Sekoia.io"
		id = "9f5b85c4-59e3-448f-b054-5b4932ee89bb"
		date = "2023-08-29"
		modified = "2024-12-19"
		reference = "https://github.com/SEKOIA-IO/Community"
		source_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/yara_rules/bot_win_yamabot.yar#L1-L20"
		license_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/LICENSE.md"
		hash = "1e4de822695570421eb2f12fdfe1d32ab8639655e12180a7ab3cf429e7811b8f"
		hash = "66415464a0795d0569efa5cb5664785f74ed0b92a593280d689f3a2ac68dca66"
		hash = "74529dd15d1953a47f0d7ecc2916b2b92865274a106e453a24943ca9ee434643"
		hash = "def2f01fbd4be85f48101e5ab7ddd82efb720e67daa6838f30fd8dcda1977563"
		logic_hash = "cb183cbf9703d96b5f463d635885eab66e0d36c4763752a5cb934538ada60ec3"
		score = 75
		quality = 80
		tags = "FILE"
		version = "1.0"
		classification = "TLP:CLEAR"

	strings:
		$s1 = "_/D_/Bot/YamaBot/"
		$s2 = "Go build ID: \"ujRRNborth3MgXzS7HTu/aYhLszO8_95srnr8Fk1n/Xr8P792kGZ_VUqOQVc97/kgx_H7YuMZBl2Ajyac2M\""

	condition:
		uint16be( 0 ) == 0x4d5a and 1 of them and filesize > 3MB
}

Strings (2 patterns)

Identifier	Type	Value	Modifiers
$s1	text	"_/D_/Bot/YamaBot/"
$s2	text	"Go build ID: \"ujRRNborth3MgXzS7HTu/aYhLszO8_95srnr8Fk1n/Xr8P792kGZ_VUqOQVc97/kgx_H7YuMZBl2Ajyac2M\""

Condition

uint16be( 0 ) == 0x4d5a and 1 of them and filesize > 3MB

In plain words (Heuristic)

The file must start with “MZ” — a Windows executable (PE).
The file must be larger than 3MB.
At least 1 patterns in the rule must match.

Test this rule in your browser

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

Open in editor

References

https://github.com/SEKOIA-IO/Community

Sample hashes

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

1e4de822695570421eb2f12fdfe1d32ab8639655e12180a7ab3cf429e7811b8f
66415464a0795d0569efa5cb5664785f74ed0b92a593280d689f3a2ac68dca66
74529dd15d1953a47f0d7ecc2916b2b92865274a106e453a24943ca9ee434643
def2f01fbd4be85f48101e5ab7ddd82efb720e67daa6838f30fd8dcda1977563

Licence & attribution

Author: Sekoia.io

Source repository: SEKOIA.IO Community @ a438a5901a

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: 9f5b85c4-59e3-448f-b054-5b4932ee89bb

Metadata

version	1.0
classification	TLP:CLEAR

Tags:FILE

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