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SEKOIA_Backdoor_Win_Kimsuky

Detect the backdoors used by Kimsuky based on specific PE ressources

MalwareKimsukySEKOIA.IO CommunityDetection Rule License 1.1Compiles with YARA-X (with warnings)
Author
Sekoia.io
Date
2024-06-04
Modified
2024-12-19
Score / Quality
75 / 80

What this rule detects

Detect the backdoors used by Kimsuky based on specific PE ressources

Associated malware family: Kimsuky.

Targets: Windows PE.

It has no patterns: the condition alone decides (modules, file properties or other rules). YARA modules used: pe, hash.

YARA-X says: warning[deprecated_field]: field `number_of_resources` is deprecated

Summary generated from the rule's metadata and condition.

Rule source

Includes the imports needed to compile it on its own.

backdoor-win-kimsuky.yarDetection Rule License 1.1
import "pe"
import "hash"

rule SEKOIA_Backdoor_Win_Kimsuky : FILE
{
	meta:
		description = "Detect the backdoors used by Kimsuky based on specific PE ressources"
		author = "Sekoia.io"
		id = "db927d1c-34cf-4501-a6ce-3e8ecdefc5a3"
		date = "2024-06-04"
		modified = "2024-12-19"
		reference = "https://github.com/SEKOIA-IO/Community"
		source_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/yara_rules/backdoor_win_kimsuky.yar#L4-L38"
		license_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/LICENSE.md"
		hash = "000e2926f6e094d01c64ff972e958cd38590299e9128a766868088aa273599c7"
		hash = "cca1705d7a85fe45dce9faec5790d498427b3fa8e546d7d7b57f18a925fdfa5d"
		logic_hash = "ba40427f7e305a6e6cec6bb0165b49e6ce215ecf66fc2e05954c10e4d9acf9b0"
		score = 75
		quality = 80
		tags = "FILE"
		version = "1.0"
		classification = "TLP:CLEAR"

	condition:
		uint16be( 0 ) == 0x4d5a and for any i in ( 0 .. pe.number_of_resources -1 ) : ( hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "3d570af85db2bb18265d80e7209a5c90f7cc82e0c868c0088a925df6f34e9066" or hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "3d570af85db2bb18265d80e7209a5c90f7cc82e0c868c0088a925df6f34e9066" or hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "ac9ed305c6dac749163db359736e7d92fca9173ff5c9e1f021d500b306e3c5ec" or hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "0ca965ccf7324b098da617909d38986c1e6aae3e12d9629975f1815ed4ed3907" or hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "25d79e59a6b625e5c22ccb55cc49373d38cc6f20cb75504b0df1bc0804bb1247" or hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "ce5619ffe04ec569bf2565e0964156378bda7c42eb646bedbac2191a5af7bebf" or hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "ce10e65f7bf105fc06005340f0a8eaea9b351f3750d2818c1cf2ca25a7f495be" or hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "5a9e2a392c530ab8b38ff917ae0f28496107f1bde94e89515931fd29a0bfb2e5" or hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "19f4f3a05b809d8e33bb0004f62899ca5f9eac7e4cdba68dfd5c0a6f2d71bec3" or hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "b9c208b9bada7bac4d5bfe53992f570e34e0b4d5cfa0862de9847ddf5630ab9a" or hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "3d570af85db2bb18265d80e7209a5c90f7cc82e0c868c0088a925df6f34e9066" or hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "ac9ed305c6dac749163db359736e7d92fca9173ff5c9e1f021d500b306e3c5ec" or hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "0ca965ccf7324b098da617909d38986c1e6aae3e12d9629975f1815ed4ed3907" or hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "25d79e59a6b625e5c22ccb55cc49373d38cc6f20cb75504b0df1bc0804bb1247" or hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "ce5619ffe04ec569bf2565e0964156378bda7c42eb646bedbac2191a5af7bebf" or hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "ce10e65f7bf105fc06005340f0a8eaea9b351f3750d2818c1cf2ca25a7f495be" or hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "5a9e2a392c530ab8b38ff917ae0f28496107f1bde94e89515931fd29a0bfb2e5" or hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "19f4f3a05b809d8e33bb0004f62899ca5f9eac7e4cdba68dfd5c0a6f2d71bec3" or hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "b9c208b9bada7bac4d5bfe53992f570e34e0b4d5cfa0862de9847ddf5630ab9a" )
}

Condition

uint16be( 0 ) == 0x4d5a and for any i in ( 0 .. pe.number_of_resources -1 ) : ( hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "3d570af85db2bb18265d80e7209a5c90f7cc82e0c868c0088a925df6f34e9066" or hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "3d570af85db2bb18265d80e7209a5c90f7cc82e0c868c0088a925df6f34e9066" or hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "ac9ed305c6dac749163db359736e7d92fca9173ff5c9e1f021d500b306e3c5ec" or hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "0ca965ccf7324b098da617909d38986c1e6aae3e12d9629975f1815ed4ed3907" or hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "25d79e59a6b625e5c22ccb55cc49373d38cc6f20cb75504b0df1bc0804bb1247" or hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "ce5619ffe04ec569bf2565e0964156378bda7c42eb646bedbac2191a5af7bebf" or hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "ce10e65f7bf105fc06005340f0a8eaea9b351f3750d2818c1cf2ca25a7f495be" or hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "5a9e2a392c530ab8b38ff917ae0f28496107f1bde94e89515931fd29a0bfb2e5" or hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "19f4f3a05b809d8e33bb0004f62899ca5f9eac7e4cdba68dfd5c0a6f2d71bec3" or hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "b9c208b9bada7bac4d5bfe53992f570e34e0b4d5cfa0862de9847ddf5630ab9a" or hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "3d570af85db2bb18265d80e7209a5c90f7cc82e0c868c0088a925df6f34e9066" or hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "ac9ed305c6dac749163db359736e7d92fca9173ff5c9e1f021d500b306e3c5ec" or hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "0ca965ccf7324b098da617909d38986c1e6aae3e12d9629975f1815ed4ed3907" or hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "25d79e59a6b625e5c22ccb55cc49373d38cc6f20cb75504b0df1bc0804bb1247" or hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "ce5619ffe04ec569bf2565e0964156378bda7c42eb646bedbac2191a5af7bebf" or hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "ce10e65f7bf105fc06005340f0a8eaea9b351f3750d2818c1cf2ca25a7f495be" or hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "5a9e2a392c530ab8b38ff917ae0f28496107f1bde94e89515931fd29a0bfb2e5" or hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "19f4f3a05b809d8e33bb0004f62899ca5f9eac7e4cdba68dfd5c0a6f2d71bec3" or hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "b9c208b9bada7bac4d5bfe53992f570e34e0b4d5cfa0862de9847ddf5630ab9a" )

In plain words (Heuristic)

  • The file must start with “MZ” — a Windows executable (PE).
  • A for-loop checks a property over several matches or items.
  • Uses the pe module.
  • Uses the hash module.
  • Compares a hash of the file or a part of it.

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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).

  • 000e2926f6e094d01c64ff972e958cd38590299e9128a766868088aa273599c7
  • cca1705d7a85fe45dce9faec5790d498427b3fa8e546d7d7b57f18a925fdfa5d

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: db927d1c-34cf-4501-a6ce-3e8ecdefc5a3

Metadata

version1.0
classificationTLP:CLEAR

Tags:FILE

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