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YARA · Trellix Advanced Research Center

TRELLIX_ARC_Wannaren_Ransomware

Rule to detect WannaRen Ransomware

MalwareWannaRenTrellix Advanced Research CenterApache License 2.0Compiles with YARA-X
Author
McAfee ATR Team
Date
2020-04-25
Modified
2020-10-12
Score / Quality
75 / 70

What this rule detects

Rule to detect WannaRen Ransomware

Associated malware family: WannaRen.

Targets: Windows PE.

It defines 10 patterns (0 text, 10 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

wannaren-ransomware.yarApache License 2.0
rule TRELLIX_ARC_Wannaren_Ransomware : RANSOMWARE FILE
{
	meta:
		description = "Rule to detect WannaRen Ransomware"
		author = "McAfee ATR Team"
		id = "f4f30d12-547d-5044-a4e5-b88bf359480f"
		date = "2020-04-25"
		modified = "2020-10-12"
		reference = "https://blog.360totalsecurity.com/en/attention-you-may-have-become-a-susceptible-group-of-wannaren-ransomware/"
		source_url = "https://github.com/advanced-threat-research/Yara-Rules//blob/1919562a59f190bda60c982424f6a24c542ee3e0/ransomware/RANSOM_wannaren.yar#L1-L34"
		license_url = "https://github.com/advanced-threat-research/Yara-Rules//blob/1919562a59f190bda60c982424f6a24c542ee3e0/LICENSE"
		hash = "7b364f1c854e6891c8d09766bcc9a49420e0b5b4084d74aa331ae94e2cfb7e1d"
		logic_hash = "0feb913b84eb0ecdda688f0cf0a5051798fe4fbce8a6ea959825985a81a6699c"
		score = 75
		quality = 70
		tags = "RANSOMWARE, FILE"
		rule_version = "v1"
		malware_type = "ransomware"
		malware_family = "Ransom:W32/WannaRen"
		actor_type = "Cybercrime"
		actor_group = "Unknown"

	strings:
		$sq0 = { 92 93 a91c2ea521 59 334826 }
		$sq1 = { d0ce 6641 c1e9c0 41 80f652 49 c1f94d }
		$sq2 = { 80f8b5 4d 63c9 f9 4d 03d9 41 }
		$sq3 = { 34b7 d2ea 660fbafa56 0f99c2 32d8 660fbafaed 99 }
		$sq4 = { f9 f7c70012355f 35c01f5226 f9 8d8056c800b0 f6c4b2 f9 }
		$sq5 = { f5 f9 44 3aeb 45 33cd 41 }
		$sq6 = { 890f c0ff12 44 b4a3 ee 2b4e70 7361 }
		$sq7 = { 81c502000000 6689542500 6681d97a1e 660fabe1 660fbae1a5 8b0f 8dbf04000000 }
		$sq8 = { 8d13 de11 d7 677846 f1 0d8cd45f87 bb34b98f33 }
		$sq9 = { 1440 4b 41 e8???????? 397c0847 }

	condition:
		uint16( 0 ) == 0x5a4d and filesize < 21000KB and 7 of them
}

Strings (10 patterns)

IdentifierTypeValueModifiers
$sq0hex{ 92 93 a91c2ea521 59 334826 }
$sq1hex{ d0ce 6641 c1e9c0 41 80f652 49 c1f94d }
$sq2hex{ 80f8b5 4d 63c9 f9 4d 03d9 41 }
$sq3hex{ 34b7 d2ea 660fbafa56 0f99c2 32d8 660fbafaed 99 }
$sq4hex{ f9 f7c70012355f 35c01f5226 f9 8d8056c800b0 f6c4b2 f9 }
$sq5hex{ f5 f9 44 3aeb 45 33cd 41 }
$sq6hex{ 890f c0ff12 44 b4a3 ee 2b4e70 7361 }
$sq7hex{ 81c502000000 6689542500 6681d97a1e 660fabe1 660fbae1a5 8b0f 8dbf04000000 }
$sq8hex{ 8d13 de11 d7 677846 f1 0d8cd45f87 bb34b98f33 }
$sq9hex{ 1440 4b 41 e8???????? 397c0847 }

Condition

uint16( 0 ) == 0x5a4d and filesize < 21000KB and 7 of them

In plain words (Heuristic)

  • The file must start with “MZ” — a Windows executable (PE).
  • The file must be smaller than 21000KB (a cheap guard that skips large files).
  • At least 7 patterns in the rule must match.

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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).

  • 7b364f1c854e6891c8d09766bcc9a49420e0b5b4084d74aa331ae94e2cfb7e1d

Licence & attribution

Author: McAfee ATR Team

Source repository: Trellix Advanced Research Center @ 1919562a59

Licence: Apache License 2.0 (repository licence)

Original rule

Mirrored via YARA Forge 20260927, which prefixes rule names with the source and adds normalised meta fields.

Rule id: f4f30d12-547d-5044-a4e5-b88bf359480f

Metadata

rule_versionv1
malware_typeransomware
malware_familyRansom:W32/WannaRen
actor_typeCybercrime
actor_groupUnknown

Tags:RANSOMWAREFILE