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YARA · Signature Base (Florian Roth / Nextron)

SIGNATURE_BASE_MAL_Prolock_Malware

Detects Prolock malware in encrypted and decrypted mode

MalwareProlockSignature Base (Florian Roth / Nextron)Detection Rule License 1.1Compiles with YARA-X
Author
Frank Boldewin (@r3c0nst)
Date
2020-05-17
Modified
2023-12-05
Score / Quality
75 / 85

What this rule detects

Detects Prolock malware in encrypted and decrypted mode

Associated malware family: Prolock.

Targets: Windows PE.

It defines 5 patterns (3 text, 2 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

Download .yar
mal-prolock-malware.yarDetection Rule License 1.1
rule SIGNATURE_BASE_MAL_Prolock_Malware : FILE
{
	meta:
		description = "Detects Prolock malware in encrypted and decrypted mode"
		author = "Frank Boldewin (@r3c0nst)"
		id = "269bf0c5-8315-5405-8e44-e2cc5507a36a"
		date = "2020-05-17"
		modified = "2023-12-05"
		reference = "https://raw.githubusercontent.com/fboldewin/YARA-rules/master/Prolock.Malware.yar"
		source_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/crime_ransom_prolock.yar#L1-L20"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		hash = "a6ded68af5a6e5cc8c1adee029347ec72da3b10a439d98f79f4b15801abd7af0"
		hash = "dfbd62a3d1b239601e17a5533e5cef53036647901f3fb72be76d92063e279178"
		logic_hash = "da8a0ec683475019daddd4acdd00d4c36eedacad3deef2be4220b86cbf5f9df0"
		score = 75
		quality = 85
		tags = "FILE"

	strings:
		$DecryptionRoutine = {01 C2 31 DB B8 ?? ?? ?? ?? 31 04 1A 81 3C 1A}
		$DecryptedString1 = "support981723721@protonmail.com" nocase ascii
		$DecryptedString2 = "Your files have been encrypted by ProLock Ransomware" nocase ascii
		$DecryptedString3 = "msaoyrayohnp32tcgwcanhjouetb5k54aekgnwg7dcvtgtecpumrxpqd.onion" nocase ascii
		$CryptoCode = {B8 63 51 E1 B7 31 D2 8D BE ?? ?? ?? ?? B9 63 51 E1 B7 81 C1 B9 79 37 9E}

	condition:
		(( uint16( 0 ) == 0x5A4D ) or ( uint16( 0 ) == 0x4D42 ) ) and filesize < 100KB and ( ( $DecryptionRoutine ) or ( 1 of ( $DecryptedString* ) and $CryptoCode ) )
}

Strings (5 patterns)

IdentifierTypeValueModifiers
$DecryptionRoutinehex{01 C2 31 DB B8 ?? ?? ?? ?? 31 04 1A 81 3C 1A}
$DecryptedString1text"support981723721@protonmail.com"nocase ascii
$DecryptedString2text"Your files have been encrypted by ProLock Ransomware"nocase ascii
$DecryptedString3text"msaoyrayohnp32tcgwcanhjouetb5k54aekgnwg7dcvtgtecpumrxpqd.onion"nocase ascii
$CryptoCodehex{B8 63 51 E1 B7 31 D2 8D BE ?? ?? ?? ?? B9 63 51 E1 B7 81 C1 B9 79 37 9E}

Condition

(( uint16( 0 ) == 0x5A4D ) or ( uint16( 0 ) == 0x4D42 ) ) and filesize < 100KB and ( ( $DecryptionRoutine ) or ( 1 of ( $DecryptedString* ) and $CryptoCode ) )

In plain words (Heuristic)

  • The file must start with “MZ” — a Windows executable (PE).
  • The file must be smaller than 100KB (a cheap guard that skips large files).
  • At least 1 patterns in ( $DecryptedString* ) must match.
  • Pattern $CryptoCode must be present.

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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).

  • a6ded68af5a6e5cc8c1adee029347ec72da3b10a439d98f79f4b15801abd7af0
  • dfbd62a3d1b239601e17a5533e5cef53036647901f3fb72be76d92063e279178

Licence & attribution

Author: Frank Boldewin (@r3c0nst)

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: 269bf0c5-8315-5405-8e44-e2cc5507a36a

Tags:FILE

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