YARA · SEKOIA.IO Community

SEKOIA_Apt_Aptk47_Asyncshell

Detects APT-K-47's Asyncshell

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

Author: Sekoia.io
Date: 2024-11-22
Modified: 2024-12-19
Score / Quality: 75 / 80

What this rule detects

Detects APT-K-47's Asyncshell

Targets: Windows PE.

It defines 6 patterns (6 text, 0 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

Download .yar

apt-aptk47-asyncshell.yarDetection Rule License 1.1

rule SEKOIA_Apt_Aptk47_Asyncshell : FILE
{
	meta:
		description = "Detects APT-K-47's Asyncshell"
		author = "Sekoia.io"
		id = "2d009cf4-e30e-406d-8860-03b37a396ffa"
		date = "2024-11-22"
		modified = "2024-12-19"
		reference = "https://github.com/SEKOIA-IO/Community"
		source_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/yara_rules/apt_aptk47_asyncshell.yar#L1-L24"
		license_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/LICENSE.md"
		hash = "ce6a589d5e3604112e5595a1f8d53e1e"
		hash = "751f427da8e11d8ab394574260735220"
		logic_hash = "ac202f7dc317d17118badf71c32776c5666eea4a47e1b439a287b6b8766e9da6"
		score = 75
		quality = 80
		tags = "FILE"
		version = "1.0"
		classification = "TLP:CLEAR"

	strings:
		$ = "Error executing command:" wide
		$ = "Error occurred:" wide
		$ = "Attempting to reconnect in {0} seconds..." wide
		$ = "Exiting the application." wide
		$ = "Server disconnected." wide
		$ = "_CorExeMain"

	condition:
		uint16be( 0 ) == 0x4d5a and filesize < 1MB and 4 of them
}

Strings (6 patterns)

Identifier	Type	Value	Modifiers
$	text	"Error executing command:"	wide
$	text	"Error occurred:"	wide
$	text	"Attempting to reconnect in {0} seconds..."	wide
$	text	"Exiting the application."	wide
$	text	"Server disconnected."	wide
$	text	"_CorExeMain"

Condition

uint16be( 0 ) == 0x4d5a and filesize < 1MB and 4 of them

In plain words (Heuristic)

The file must start with “MZ” — a Windows executable (PE).
The file must be smaller than 1MB (a cheap guard that skips large files).
At least 4 patterns in the rule must match.

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References

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

Sample hashes

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

ce6a589d5e3604112e5595a1f8d53e1e
751f427da8e11d8ab394574260735220

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: 2d009cf4-e30e-406d-8860-03b37a396ffa

Metadata

version	1.0
classification	TLP:CLEAR

Tags:FILE

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