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SEKOIA_Infostealer_Win_Monster_Stub

Finds Monster Stealer stub (Python payload) based on specific strings.

MalwareSEKOIA.IO CommunityDetection Rule License 1.1Compiles with YARA-X
Author
Sekoia.io
Date
2024-08-07
Modified
2024-12-19
Score / Quality
75 / 80

What this rule detects

Finds Monster Stealer stub (Python payload) based on specific strings.

Targets: Windows PE.

It defines 17 patterns (17 text, 0 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

infostealer-win-monster-stub.yarDetection Rule License 1.1
rule SEKOIA_Infostealer_Win_Monster_Stub : FILE
{
	meta:
		description = "Finds Monster Stealer stub (Python payload) based on specific strings."
		author = "Sekoia.io"
		id = "10d27d49-79ae-4edc-8c30-35506bdf2c42"
		date = "2024-08-07"
		modified = "2024-12-19"
		reference = "https://github.com/SEKOIA-IO/Community"
		source_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/yara_rules/infostealer_win_monster_stub.yar#L1-L31"
		license_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/LICENSE.md"
		logic_hash = "d6362c54b1f56ffa878423fbb1a3f57508d20e06b573c732f892494178a49200"
		score = 75
		quality = 80
		tags = "FILE"
		version = "1.0"
		classification = "TLP:CLEAR"

	strings:
		$str01 = "https://t.me/monster_free_cloud" ascii
		$str02 = "MonsterUpdateService" ascii
		$str03 = "Monster.exe" ascii
		$str04 = "schtasks /create /f /sc daily /ri 30 /tn" ascii
		$str05 = "C:\\ProgramData\\Microsoft\\Windows\\Start Menu\\Programs\\StartUp\\" ascii
		$str06 = "banned_uuids" ascii
		$str07 = "banned_computer_names" ascii
		$str08 = "banned_process" ascii
		$str09 = "register_X_browsers" ascii
		$str10 = "register_payload" ascii
		$str11 = "tiktok_sessions.txt" ascii
		$str12 = "spotify_sessions.txt" ascii
		$str13 = "network_info.txt" ascii
		$str14 = "lolz.guru" ascii
		$str15 = "echo ####System Info####" ascii
		$str16 = "echo ####Firewallinfo####" ascii
		$str17 = "/injection/main/injection.js" ascii

	condition:
		uint16( 0 ) == 0x5A4D and 10 of them
}

Strings (17 patterns)

IdentifierTypeValueModifiers
$str01text"https://t.me/monster_free_cloud"ascii
$str02text"MonsterUpdateService"ascii
$str03text"Monster.exe"ascii
$str04text"schtasks /create /f /sc daily /ri 30 /tn"ascii
$str05text"C:\\ProgramData\\Microsoft\\Windows\\Start Menu\\Programs\\StartUp\\"ascii
$str06text"banned_uuids"ascii
$str07text"banned_computer_names"ascii
$str08text"banned_process"ascii
$str09text"register_X_browsers"ascii
$str10text"register_payload"ascii
$str11text"tiktok_sessions.txt"ascii
$str12text"spotify_sessions.txt"ascii
$str13text"network_info.txt"ascii
$str14text"lolz.guru"ascii
$str15text"echo ####System Info####"ascii
$str16text"echo ####Firewallinfo####"ascii
$str17text"/injection/main/injection.js"ascii

Condition

uint16( 0 ) == 0x5A4D and 10 of them

In plain words (Heuristic)

  • The file must start with “MZ” — a Windows executable (PE).
  • At least 10 patterns in the rule must match.

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References

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: 10d27d49-79ae-4edc-8c30-35506bdf2c42

Metadata

version1.0
classificationTLP:CLEAR

Tags:FILE