Skip to content

YARA · SEKOIA.IO Community

SEKOIA_Apt_Apt41_Keyplug_Dropper

Detects a dropper used by keyplug

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

What this rule detects

Detects a dropper used by keyplug

Targets: Windows PE.

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

Summary generated from the rule's metadata and condition.

Rule source

apt-apt41-keyplug-dropper.yarDetection Rule License 1.1
rule SEKOIA_Apt_Apt41_Keyplug_Dropper : FILE
{
	meta:
		description = "Detects a dropper used by keyplug"
		author = "Sekoia.io"
		id = "b6740371-c4c3-437e-8235-0bd4f7b9c3f5"
		date = "2024-06-12"
		modified = "2024-12-19"
		reference = "https://github.com/SEKOIA-IO/Community"
		source_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/yara_rules/apt_apt41_keyplug_dropper.yar#L1-L20"
		license_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/LICENSE.md"
		logic_hash = "a61f57302d8fe58ed8b77542c94159acbc36a3bd52c204171e76e668d10a74e7"
		score = 75
		quality = 80
		tags = "FILE"
		version = "1.0"
		classification = "TLP:CLEAR"

	strings:
		$ = "C:\\ProgramData\\pfm.ico" wide
		$ = "C:\\\\ProgramData\\\\pfm.ico" wide
		$ = "67f8de349abc5ghi" wide
		$ = "3abc64597f8diegh" wide

	condition:
		uint16be( 0 ) == 0x4d5a and filesize < 2MB and any of them
}

Strings (4 patterns)

IdentifierTypeValueModifiers
$text"C:\\ProgramData\\pfm.ico"wide
$text"C:\\\\ProgramData\\\\pfm.ico"wide
$text"67f8de349abc5ghi"wide
$text"3abc64597f8diegh"wide

Condition

uint16be( 0 ) == 0x4d5a and filesize < 2MB and any of them

In plain words (Heuristic)

  • The file must start with “MZ” — a Windows executable (PE).
  • The file must be smaller than 2MB (a cheap guard that skips large files).
  • At least one pattern in the rule must match.

Test this rule in your browser

Drop a file to scan it with this rule using YARA-X compiled to WebAssembly. Nothing is uploaded.

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

Open in editor

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: b6740371-c4c3-437e-8235-0bd4f7b9c3f5

Metadata

version1.0
classificationTLP:CLEAR

Tags:FILE