YARA · Signature Base (Florian Roth / Nextron)

SIGNATURE_BASE_APT_MAL_Revil_Kaseya_Jul21_1

Detects malware used in the Kaseya supply chain attack

APT / threat actorRevilSignature Base (Florian Roth / Nextron)Detection Rule License 1.1Compiles with YARA-X

Author: Florian Roth (Nextron Systems)
Date: 2021-07-02
Modified: 2023-12-05
Score / Quality: 75 / 85

What this rule detects

Detects malware used in the Kaseya supply chain attack

Associated malware family: Revil.

Targets: Windows PE.

It defines 7 patterns (2 text, 5 hex, 0 regex). YARA modules used: pe.

Summary generated from the rule's metadata and condition.

Rule source

Download .yar

Includes the imports needed to compile it on its own.

apt-mal-revil-kaseya-jul21-1.yarDetection Rule License 1.1

import "pe"

rule SIGNATURE_BASE_APT_MAL_Revil_Kaseya_Jul21_1 : FILE
{
	meta:
		description = "Detects malware used in the Kaseya supply chain attack"
		author = "Florian Roth (Nextron Systems)"
		id = "7356f4ea-183f-52ec-a167-fc16b8bfb55a"
		date = "2021-07-02"
		modified = "2023-12-05"
		reference = "https://doublepulsar.com/kaseya-supply-chain-attack-delivers-mass-ransomware-event-to-us-companies-76e4ec6ec64b"
		source_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/crime_revil_general.yar#L3-L30"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		hash = "1fe9b489c25bb23b04d9996e8107671edee69bd6f6def2fe7ece38a0fb35f98e"
		hash = "aae6e388e774180bc3eb96dad5d5bfefd63d0eb7124d68b6991701936801f1c7"
		hash = "dc6b0e8c1e9c113f0364e1c8370060dee3fcbe25b667ddeca7623a95cd21411f"
		hash = "df2d6ef0450660aaae62c429610b964949812df2da1c57646fc29aa51c3f031e"
		logic_hash = "a7f9fa8f8e8a3a25728aa6a334924e0b4075f3422df6b92a2f544bb0ebb6bfad"
		score = 75
		quality = 85
		tags = "FILE"

	strings:
		$s1 = "Mpsvc.dll" wide fullword
		$s2 = ":0:4:8:<:@:D:H:L:P:T:X:\\:`:d:h:l:p:t:x:H<L<P<\\<`<" ascii fullword
		$op1 = { 40 87 01 c3 6a 08 68 f8 0e 41 00 e8 ae db ff ff be 80 25 41 00 39 35 ?? 32 41 00 }
		$op2 = { 8b 40 04 2b c2 c1 f8 02 3b c8 0f 84 56 ff ff ff 68 15 50 40 00 2b c1 6a 04 }
		$op3 = { 74 73 db e2 e8 ad 07 00 00 68 60 1a 40 00 e8 8f 04 00 00 e8 3a 05 00 00 50 e8 25 26 00 00 }
		$op4 = { 75 05 8b 45 fc eb 4c c7 45 f8 00 00 00 00 6a 00 8d 45 f0 50 8b 4d 0c }
		$op5 = { 83 7d 0c 00 75 05 8b 45 fc eb 76 6a 00 68 80 00 00 00 6a 01 6a 00 }

	condition:
		uint16( 0 ) == 0x5a4d and filesize < 3000KB and ( pe.imphash ( ) == "c36dcd2277c4a707a1a645d0f727542a" or 2 of them )
}

Strings (7 patterns)

Identifier	Type	Value	Modifiers
$s1	text	"Mpsvc.dll"	wide fullword
$s2	text	":0:4:8:<:@:D:H:L:P:T:X:\\:`:d:h:l:p:t:x:H<L<P<\\<`<"	ascii fullword
$op1	hex	{ 40 87 01 c3 6a 08 68 f8 0e 41 00 e8 ae db ff ff be 80 25 41 00 39 35 ?? 32 41 00 }
$op2	hex	{ 8b 40 04 2b c2 c1 f8 02 3b c8 0f 84 56 ff ff ff 68 15 50 40 00 2b c1 6a 04 }
$op3	hex	{ 74 73 db e2 e8 ad 07 00 00 68 60 1a 40 00 e8 8f 04 00 00 e8 3a 05 00 00 50 e8 25 26 00 00 }
$op4	hex	{ 75 05 8b 45 fc eb 4c c7 45 f8 00 00 00 00 6a 00 8d 45 f0 50 8b 4d 0c }
$op5	hex	{ 83 7d 0c 00 75 05 8b 45 fc eb 76 6a 00 68 80 00 00 00 6a 01 6a 00 }

Condition

uint16( 0 ) == 0x5a4d and filesize < 3000KB and ( pe.imphash ( ) == "c36dcd2277c4a707a1a645d0f727542a" or 2 of them )

In plain words (Heuristic)

The file must start with “MZ” — a Windows executable (PE).
The file must be smaller than 3000KB (a cheap guard that skips large files).
At least 2 patterns in the rule must match.
Uses the pe module.
Checks the PE import hash (imphash).

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

https://doublepulsar.com/kaseya-supply-chain-attack-delivers-mass-ransomware-event-to-us-companies-76e4ec6ec64b

Sample hashes

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

1fe9b489c25bb23b04d9996e8107671edee69bd6f6def2fe7ece38a0fb35f98e
aae6e388e774180bc3eb96dad5d5bfefd63d0eb7124d68b6991701936801f1c7
dc6b0e8c1e9c113f0364e1c8370060dee3fcbe25b667ddeca7623a95cd21411f
df2d6ef0450660aaae62c429610b964949812df2da1c57646fc29aa51c3f031e

Licence & attribution

Author: Florian Roth (Nextron Systems)

Source repository: Signature Base (Florian Roth / Nextron) @ 94a1c48d7a

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: 7356f4ea-183f-52ec-a167-fc16b8bfb55a

Tags:FILE

SIGNATURE_BASE_APT_MAL_Revil_Kaseya_Jul21_2
APT / threat actorSignature Base (Florian Roth / Nextron)· Florian Roth (Nextron Systems)· 2021-07-02
SIGNATURE_BASE_MAL_RANSOM_Revil_Oct20_1
MalwareSignature Base (Florian Roth / Nextron)· Florian Roth (Nextron Systems)· 2020-10-13
MALPEDIA_Win_Revil_Auto
MalwareMalpedia signator rules· Felix Bilstein - yara-signator at cocacoding dot com· 2026-05-04
SEKOIA_Loader_Win_Revil_Loader
MalwareSEKOIA.IO Community· Sekoia.io· 2021-07-19
ARKBIRD_SOLG_RAN_ELF_Revil_Jun_2021_1Metadata only
MalwareArkbird SOLG (DailyIOC)· Arkbird_SOLG· 2021-06-28
SIGNATURE_BASE_APT_HKTL_Wiper_Whispergate_Jan22_2
APT / threat actorSignature Base (Florian Roth / Nextron)· Florian Roth (Nextron Systems)· 2022-01-16
SIGNATURE_BASE_APT_HKTL_Wiper_Whispergate_Jan22_1
APT / threat actorSignature Base (Florian Roth / Nextron)· Florian Roth (Nextron Systems)· 2022-01-16
SIGNATURE_BASE_APT_UA_Hermetic_Wiper_Scheduled_Task_Feb22_1
APT / threat actorSignature Base (Florian Roth / Nextron)· Florian Roth (Nextron Systems)· 2022-02-25

More Revil rules