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YARA · Trellix Advanced Research Center

TRELLIX_ARC_Pwnlnx_Backdoor_Variant_6

Rule to detect the backdoor pwnlnx variant 6

MalwarePwnlnxTrellix Advanced Research CenterApache License 2.0Compiles with YARA-X
Author
Marc Rivero | McAfee ATR Team
Date
2020-04-17
Modified
2020-08-14
Score / Quality
75 / 70

What this rule detects

Rule to detect the backdoor pwnlnx variant 6

Associated malware family: Pwnlnx.

It defines 1 patterns (0 text, 1 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

pwnlnx-backdoor-variant-6.yarApache License 2.0
rule TRELLIX_ARC_Pwnlnx_Backdoor_Variant_6 : BACKDOOR FILE
{
	meta:
		description = "Rule to detect the backdoor pwnlnx variant 6"
		author = "Marc Rivero | McAfee ATR Team"
		id = "56bfe9c7-4cd4-51f6-a469-da8af52d64c2"
		date = "2020-04-17"
		modified = "2020-08-14"
		reference = "https://www.blackberry.com/content/dam/blackberry-com/asset/enterprise/pdf/direct/report-bb-decade-of-the-rats.pdf"
		source_url = "https://github.com/advanced-threat-research/Yara-Rules//blob/1919562a59f190bda60c982424f6a24c542ee3e0/APT/APT_decade_of_RATs.yar#L131-L161"
		license_url = "https://github.com/advanced-threat-research/Yara-Rules//blob/1919562a59f190bda60c982424f6a24c542ee3e0/LICENSE"
		hash = "d29254ab907c9ef54349de3ec0dd8b22b4692c58ed7a7b340afbc6e44363f96a"
		logic_hash = "29423135a46ee7b9aa1bd8f1e6f7ffad09725787ad6e75312e1d34b18e3917d4"
		score = 75
		quality = 70
		tags = "BACKDOOR, FILE"
		rule_version = "v1"
		malware_type = "backdoor"
		malware_family = "Backdoor:W32/Pwnlnx"
		actor_type = "Cybercrime"
		actor_group = "Unknown"

	strings:
		$bp = { 7F??4C4602??01??000000000000000001??3E????000000000000000000000000000000000000??????09??00000000000000004000000000??????2B??28??04??000014??000003??0000474E55????4D9585????AB6522????52AD3B??EC9B4BE8????????0000000000000000????00000000554889??????????4889??41544989??534889??488B??????????E8????????4C89??4889??48C7??????????FF??????????488B??????????89??E8????????89??5B415C5DC30F1F??E8????????554889??????????4889??41544989??534889??488B??????????E8????????4C89??4889??48C7??????????FF??????????488B??????????89??E8????????89??5B415C5DC30F1F??E8????????554889??415541544989??534889??4883????488B??????????65??8B????????????4889????31??E8????????4889??4C89??FF??????????488B??????????4189??E8????????488B??????????483D????????488D????75??EB??0F1F??????488B????4881??????????488D????74??0FB7??488D????48C7??????????31??E8????????498B????498B??????488D????488D????????????BA????????E8????????4885??74??4981??????????????488B????65??33????????????4489??75??4883????5B415C415D5DC3E8????????0F1F??E8????????554889??415541544989??534889??4883????488B??????????65??8B????????????4889????31??E8????????4889??4C89??FF??????????488B??????????4189??E8????????488B??????????483D????????488D????75??EB??0F1F??????488B????4881??????????488D????74??0FB7??488D????48C7??????????31??E8????????498B????498B??????488D????488D????????????BA????????E8????????4885??74??4981??????????????488B????65??33????????????4489??75??4883????5B415C415D5DC3E8????????0F1F??E8????????554889??415541544989??534889??4883????488B??????????65??8B????????????4889????31??E8????????4889??4C89??FF??????????488B??????????4189??E8????????488B??????????483D????????488D????75??EB??0F1F??????488B????4881??????????488D????74??0FB7??488D????48C7??????????31??E8????????498B????498B??????488D????488D????????????BA????????E8????????4885??74??4981??????????????488B????65??33????????????4489??75??4883????5B415C415D5DC3E8????????0F1F??E8????????554889??415541544989??534889??4883????488B??????????65??8B????????????4889????31??E8????????4889??4C89??FF??????????488B??????????4189??E8????????488B??????????483D????????488D????75??EB??0F1F??????488B????4881??????????488D????74??0FB7??488D????48C7??????????31??E8????????498B????498B??????488D????488D????????????BA????????E8????????4885??74??4981??????????????488B????65??33????????????4489??75??4883????5B415C415D5DC3E8????????0F1F??E8????????554889??41574589??415641554189??4154534889??4883????488B??????????4889????4889????4C89????483D????????4C8D????74??4C63??EB??0F1F??????498B????483D????????4C8D????74??498B??4C89??4889??E8????????85??75??4883????5B415C415D415E415F5DC30F1F??????????4589??4C8B????488B????4489??4889??488B????FF??????????4883????5B415C415D415E415F5DC3660F1F??????E8????????554889??41574589??41564D89??41554989??41544189??BA????????534889??488D????4883????4889????4889??65??8B????????????4889????31??E8????????488B??????????4881??????????488D????74??0FB7????4839??75??EB??0F1F????????????410FB7????4839??74??4C8B????4981??????????498D????75??4589??4D89??4C89??4489??4889??488B????FF??????????488B????65??33????????????75??4883????5B415C415D415E415F5DC3660F1F??????31??EB??E8????????0F1F??????662E0F1F????????????E8????????55BF????????4889??4881??????????65??8B????????????4889????31??488D??????????FF????????????B9????????4889??488D??????????F3??A5488D??????????48C7??????????BE????????B1??E8????????4885??74??48BA???????? }

	condition:
		uint16( 0 ) == 0x457f and filesize < 700KB and all of them
}

Strings (1 patterns)

IdentifierTypeValueModifiers
$bphex{ 7F??4C4602??01??000000000000000001??3E????000000000000000000000000000000000000??????09??00000000000000004000000000??????2B??28??04??000014??000003??0000474E55 …

Condition

uint16( 0 ) == 0x457f and filesize < 700KB and all of them

In plain words (Heuristic)

  • The file must be smaller than 700KB (a cheap guard that skips large files).
  • All 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).

  • d29254ab907c9ef54349de3ec0dd8b22b4692c58ed7a7b340afbc6e44363f96a

Licence & attribution

Author: Marc Rivero | 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: 56bfe9c7-4cd4-51f6-a469-da8af52d64c2

Metadata

rule_versionv1
malware_typebackdoor
malware_familyBackdoor:W32/Pwnlnx
actor_typeCybercrime
actor_groupUnknown

Tags:BACKDOORFILE

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