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SEKOIA_Apt_Unk_Malicious_Lnk

Detects a malicious LNK used by an APT

APT / threat actorSEKOIA.IO CommunityDetection Rule License 1.1Compiles with YARA-X
Author
Sekoia.io
Date
2024-09-06
Modified
2024-12-19
Score / Quality
75 / 80

What this rule detects

Detects a malicious LNK used by an APT

Targets: ZIP / Office Open XML.

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

Summary generated from the rule's metadata and condition.

Rule source

apt-unk-malicious-lnk.yarDetection Rule License 1.1
rule SEKOIA_Apt_Unk_Malicious_Lnk : FILE
{
	meta:
		description = "Detects a malicious LNK used by an APT"
		author = "Sekoia.io"
		id = "d2248803-7ddf-4cde-ab6a-78b20e760919"
		date = "2024-09-06"
		modified = "2024-12-19"
		reference = "https://www.seqrite.com/blog/operation-oxidovy-sophisticated-malware-campaign-targets-czech-officials-using-nato-themed-decoys/"
		source_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/yara_rules/apt_unk_malicious_lnk.yar#L1-L21"
		license_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/LICENSE.md"
		hash = "a8d7e56eb01a8cf576533db9af2e92ec"
		logic_hash = "993411ceba45d1212a4840e6a35b72b52e64e78cbb2599ebc5c70c2fd3b8e552"
		score = 75
		quality = 80
		tags = "FILE"
		version = "1.0"
		classification = "TLP:CLEAR"

	strings:
		$ = ".pdf.lnkPK"
		$ = ".jfifPK"
		$ = ".batPK"
		$ = ".pdfPK"

	condition:
		uint32be( 0 ) == 0x504b0304 and all of them
}

Strings (4 patterns)

IdentifierTypeValueModifiers
$text".pdf.lnkPK"
$text".jfifPK"
$text".batPK"
$text".pdfPK"

Condition

uint32be( 0 ) == 0x504b0304 and all of them

In plain words (Heuristic)

  • The file must start with “PK” — a ZIP archive (also Office Open XML, JAR, APK).
  • All patterns in the rule must match.

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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).

  • a8d7e56eb01a8cf576533db9af2e92ec

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: d2248803-7ddf-4cde-ab6a-78b20e760919

Metadata

version1.0
classificationTLP:CLEAR

Tags:FILE