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FIREEYE_RT_Dropper_LNK_Lnksmasher_1

The LNKSmasher project contains a prebuilt LNK file that has pieces added based on various configuration items. Because of this, several artifacts are present in every single LNK file generated by LNKSmasher, including the Drive Serial #, the File Droid GUID, and the GUID CLSID.

MalwareMandiant red team tool countermeasuresBSD 2-Clause LicenseCompiles with YARA-X
Author
FireEye
Date
2020-12-08
Modified
2020-12-09
Score / Quality
75 / 75

What this rule detects

The LNKSmasher project contains a prebuilt LNK file that has pieces added based on various configuration items. Because of this, several artifacts are present in every single LNK file generated by LNKSmasher, including the Drive Serial #, the File Droid GUID, and the GUID CLSID.

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

Summary generated from the rule's metadata and condition.

Rule source

dropper-lnk-lnksmasher-1.yarBSD 2-Clause License
rule FIREEYE_RT_Dropper_LNK_Lnksmasher_1 : FILE
{
	meta:
		description = "The LNKSmasher project contains a prebuilt LNK file that has pieces added based on various configuration items. Because of this, several artifacts are present in every single LNK file generated by LNKSmasher, including the Drive Serial #, the File Droid GUID, and the GUID CLSID."
		author = "FireEye"
		id = "1b93ddf8-9578-5e47-b479-4c9e8a40b4f4"
		date = "2020-12-08"
		modified = "2020-12-09"
		reference = "https://github.com/mandiant/red_team_tool_countermeasures/"
		source_url = "https://github.com/mandiant/red_team_tool_countermeasures//blob/3561b71724dbfa3e2bb78106aaa2d7f8b892c43b/rules/LNKSMASHER/production/yara/Dropper_LNK_LNKSmasher_1.yar#L4-L18"
		license_url = "https://github.com/mandiant/red_team_tool_countermeasures//blob/3561b71724dbfa3e2bb78106aaa2d7f8b892c43b/LICENSE.txt"
		hash = "0a86d64c3b25aa45428e94b6e0be3e08"
		logic_hash = "61d1ac67ac0d332ad842a522cbebe1b9af1482d58a210b50fb45209355c0aeeb"
		score = 75
		quality = 75
		tags = "FILE"
		rev = 6

	strings:
		$drive_serial = { 12 F7 26 BE }
		$file_droid_guid = { BC 96 28 4F 0A 46 54 42 81 B8 9F 48 64 D7 E9 A5 }
		$guid_clsid = { E0 4F D0 20 EA 3A 69 10 A2 D8 08 00 2B 30 30 9D }
		$header = { 4C 00 00 00 01 14 02 }

	condition:
		$header at 0 and all of them
}

Strings (4 patterns)

IdentifierTypeValueModifiers
$drive_serialhex{ 12 F7 26 BE }
$file_droid_guidhex{ BC 96 28 4F 0A 46 54 42 81 B8 9F 48 64 D7 E9 A5 }
$guid_clsidhex{ E0 4F D0 20 EA 3A 69 10 A2 D8 08 00 2B 30 30 9D }
$headerhex{ 4C 00 00 00 01 14 02 }

Condition

$header at 0 and all of them

In plain words (Heuristic)

  • All patterns in the rule must match.
  • Pattern $header must be found at offset 0.

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References

Sample hashes

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

  • 0a86d64c3b25aa45428e94b6e0be3e08

Licence & attribution

Author: FireEye

Source repository: Mandiant red team tool countermeasures @ 3561b71724

Licence: BSD 2-Clause License (repository licence)

Copyright notice: Copyright (c) 2023, MANDIANT

Original rule

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

Rule id: 1b93ddf8-9578-5e47-b479-4c9e8a40b4f4

Metadata

rev6

Tags:FILE