YARA · SEKOIA.IO Community

SEKOIA_Apt_Kimsuky_Malicious_Vba

Detects malicious VBA used by Kimsuky

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

Author: Sekoia.io
Date: 2022-08-30
Modified: 2024-12-19
Score / Quality: 75 / 80

What this rule detects

Detects malicious VBA used by Kimsuky

Associated malware family: Kimsuky.

Targets: OLE / legacy Office.

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

Summary generated from the rule's metadata and condition.

Rule source

Download .yar

apt-kimsuky-malicious-vba.yarDetection Rule License 1.1

rule SEKOIA_Apt_Kimsuky_Malicious_Vba : FILE
{
	meta:
		description = "Detects malicious VBA used by Kimsuky"
		author = "Sekoia.io"
		id = "2dbe2431-3592-4395-8164-49abae4a5a3d"
		date = "2022-08-30"
		modified = "2024-12-19"
		reference = "https://github.com/SEKOIA-IO/Community"
		source_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/yara_rules/apt_kimsuky_malicious_vba.yar#L1-L18"
		license_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/LICENSE.md"
		logic_hash = "68d7b757f660907fcea3ea03c4027b429f8acdef6569d63cdb744e9d77637080"
		score = 75
		quality = 80
		tags = "FILE"
		version = "1.0"
		classification = "TLP:CLEAR"

	strings:
		$ = "Certutil -decode %TMP%"
		$ = "%LOCALAPPDATA%\\Microsoft\\Office"

	condition:
		uint32be( 0 ) == 0xD0CF11E0 and filesize < 1MB and all of them
}

Strings (2 patterns)

Identifier	Type	Value	Modifiers
$	text	"Certutil -decode %TMP%"
$	text	"%LOCALAPPDATA%\\Microsoft\\Office"

Condition

uint32be( 0 ) == 0xD0CF11E0 and filesize < 1MB and all of them

In plain words (Heuristic)

The file must start with the OLE header — legacy Office documents, MSI.
The file must be smaller than 1MB (a cheap guard that skips large files).
All 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.

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References

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

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: 2dbe2431-3592-4395-8164-49abae4a5a3d

Metadata

version	1.0
classification	TLP:CLEAR

Tags:FILE

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