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SIGNATURE_BASE_MAL_LNX_Linadoor_Rootkit_May22

Detects LinaDoor Linux Rootkit

MalwareSignature Base (Florian Roth / Nextron)Detection Rule License 1.1Compiles with YARA-X
Author
Florian Roth
Date
2022-05-19
Modified
2023-05-16
Score / Quality
85 / 85

What this rule detects

Detects LinaDoor Linux Rootkit

It defines 11 patterns (7 text, 4 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

mal-lnx-linadoor-rootkit-may22.yarDetection Rule License 1.1
rule SIGNATURE_BASE_MAL_LNX_Linadoor_Rootkit_May22 : FILE
{
	meta:
		description = "Detects LinaDoor Linux Rootkit"
		author = "Florian Roth"
		id = "e2f250b4-9a8a-5d70-83d7-5d12ad3763fb"
		date = "2022-05-19"
		modified = "2023-05-16"
		reference = "Internal Research"
		source_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/apt_lnx_linadoor_rootkit.yar#L2-L37"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		hash = "25ff1efe36eb15f8e19411886217d4c9ec30b42dca072b1bf22f041a04049cd9"
		hash = "4792e22d4c9996af1cb58ed54fee921a7a9fdd19f7a5e7f268b6793cdd1ab4e7"
		hash = "9067230a0be61347c0cf5c676580fc4f7c8580fc87c932078ad0c3f425300fb7"
		hash = "940b79dc25d1988dabd643e879d18e5e47e25d0bb61c1f382f9c7a6c545bfcff"
		hash = "a1df5b7e4181c8c1c39de976bbf6601a91cde23134deda25703bc6d9cb499044"
		hash = "c4eea99658cd82d48aaddaec4781ce0c893de42b33376b6c60a949008a3efb27"
		hash = "c5651add0c7db3bbfe0bbffe4eafe9cd5aa254d99be7e3404a2054d6e07d20e7"
		logic_hash = "546c34d4c204c7266884bb3b5b6ada418e83029ab88f72e5ffb094f50d9ed28e"
		score = 85
		quality = 85
		tags = "FILE"

	strings:
		$s1 = "/dev/net/.../rootkit_/" ascii
		$s2 = "did_exec" ascii fullword
		$s3 = "rh_reserved_tp_target" ascii fullword
		$s4 = "HIDDEN_SERVICES" ascii fullword
		$s5 = "bypass_udp_ports" ascii fullword
		$s6 = "DoBypassIP" ascii fullword
		$op1 = { 74 2a 4c 89 ef e8 00 00 00 00 48 89 da 4c 29 e2 48 01 c2 31 c0 4c 39 f2 }
		$op2 = { e8 00 00 00 00 48 89 da 4c 29 e2 48 01 c2 31 c0 4c 39 f2 48 0f 46 c3 5b }
		$op3 = { 48 89 c3 74 2a 4c 89 ef e8 00 00 00 00 48 89 da 4c 29 e2 48 01 c2 31 c0 }
		$op4 = { 4c 29 e2 48 01 c2 31 c0 4c 39 f2 48 0f 46 c3 5b 41 5c 41 5d }
		$fp1 = "/wgsyncdaemon.pid"

	condition:
		uint16( 0 ) == 0x457f and filesize < 2000KB and 2 of them and not 1 of ( $fp* ) or 4 of them
}

Strings (11 patterns)

IdentifierTypeValueModifiers
$s1text"/dev/net/.../rootkit_/"ascii
$s2text"did_exec"ascii fullword
$s3text"rh_reserved_tp_target"ascii fullword
$s4text"HIDDEN_SERVICES"ascii fullword
$s5text"bypass_udp_ports"ascii fullword
$s6text"DoBypassIP"ascii fullword
$op1hex{ 74 2a 4c 89 ef e8 00 00 00 00 48 89 da 4c 29 e2 48 01 c2 31 c0 4c 39 f2 }
$op2hex{ e8 00 00 00 00 48 89 da 4c 29 e2 48 01 c2 31 c0 4c 39 f2 48 0f 46 c3 5b }
$op3hex{ 48 89 c3 74 2a 4c 89 ef e8 00 00 00 00 48 89 da 4c 29 e2 48 01 c2 31 c0 }
$op4hex{ 4c 29 e2 48 01 c2 31 c0 4c 39 f2 48 0f 46 c3 5b 41 5c 41 5d }
$fp1text"/wgsyncdaemon.pid"

Condition

uint16( 0 ) == 0x457f and filesize < 2000KB and 2 of them and not 1 of ( $fp* ) or 4 of them

In plain words (Heuristic)

  • The file must be smaller than 2000KB (a cheap guard that skips large files).
  • At least 2 patterns in the rule must match.
  • At least 1 patterns in ( $fp* ) must match.
  • At least 4 patterns in the rule must match.

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Sample hashes

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

  • 25ff1efe36eb15f8e19411886217d4c9ec30b42dca072b1bf22f041a04049cd9
  • 4792e22d4c9996af1cb58ed54fee921a7a9fdd19f7a5e7f268b6793cdd1ab4e7
  • 9067230a0be61347c0cf5c676580fc4f7c8580fc87c932078ad0c3f425300fb7
  • 940b79dc25d1988dabd643e879d18e5e47e25d0bb61c1f382f9c7a6c545bfcff
  • a1df5b7e4181c8c1c39de976bbf6601a91cde23134deda25703bc6d9cb499044
  • c4eea99658cd82d48aaddaec4781ce0c893de42b33376b6c60a949008a3efb27
  • c5651add0c7db3bbfe0bbffe4eafe9cd5aa254d99be7e3404a2054d6e07d20e7

Licence & attribution

Author: Florian Roth

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: e2f250b4-9a8a-5d70-83d7-5d12ad3763fb

Tags:FILE