YARA · SEKOIA.IO Community

SEKOIA_Apt_Lazarus_Gopuram_Backdoor

Detects Gopuram Backdoor

APT / threat actorGopuramSEKOIA.IO CommunityDetection Rule License 1.1Compiles with YARA-X (with warnings)

Author: Sekoia.io
Date: 2023-04-04
Modified: 2024-12-19
Score / Quality: 75 / 80

What this rule detects

Detects Gopuram Backdoor

Associated malware family: Gopuram.

Targets: Windows PE.

It defines 4 patterns (1 text, 3 hex, 0 regex). YARA modules used: pe.

YARA-X says: warning[non_bool_expr]: non-boolean expression used as boolean

Summary generated from the rule's metadata and condition.

Rule source

Download .yar

Includes the imports needed to compile it on its own.

apt-lazarus-gopuram-backdoor.yarDetection Rule License 1.1

import "pe"

rule SEKOIA_Apt_Lazarus_Gopuram_Backdoor : FILE
{
	meta:
		description = "Detects Gopuram Backdoor"
		author = "Sekoia.io"
		id = "947d4ee3-79fa-450b-8482-beafe607baae"
		date = "2023-04-04"
		modified = "2024-12-19"
		reference = "https://github.com/SEKOIA-IO/Community"
		source_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/yara_rules/apt_lazarus_gopuram_backdoor.yar#L3-L24"
		license_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/LICENSE.md"
		hash = "97b95b4a5461f950e712b82783930cb2a152ec0288c00a977983ca7788342df7"
		hash = "beb775af5196f30e0ee021790a4978ca7a7ac2a7cf970a5a620ffeb89cc60b2c"
		logic_hash = "c019b65d28a7b0edf408a1a159a7535e7e14593bbd42c8df3201108ed02f96c0"
		score = 75
		quality = 80
		tags = "FILE"
		version = "1.0"
		classification = "TLP:CLEAR"

	strings:
		$x1 = "%s\\config\\TxR\\%s.TxR.0.regtrans-ms"
		$xop = {D1 E8 33 C3 D1 EB A8 01 74 ?? 81 F3 25 A3 87 DE D1 E8 33 C3 D1 EB A8 01 74 ?? 81 F3 25 A3 87 DE D1 E8 33 C3 D1 EB A8 01 74 ?? 81 F3 25 A3 87 DE D1 E8 33 C3 D1 EB A8 01 74 ?? 81 F3 25 A3 87 DE}
		$opa1 = {48 89 44 24 ?? 45 33 C9 45 33 C0 33 D2 89 5C 24 ?? 48 89 74 24 ?? 48 89 5C 24 ?? 89 7C 24 ?? FF 15 ?? ?? ?? ?? 85 C0 74 ?? 48 8B 4C 24 ?? 4C 8D 4C 24 ?? 44 8D 43 ??}
		$opa2 = {48 89 B4 24 ?? ?? ?? ?? 44 8D 43 ?? 33 D2 48 89 BC 24 ?? ?? ?? ?? 4C 89 B4 24 ?? ?? ?? ?? E8 ?? ?? ?? ?? 48 8B 4C 24 ?? E8 ?? ?? ?? ?? 48 8B 4C 24 ?? 45 33 C0 33 D2 8B F8 E8 ?? ?? ?? ?? 8D 4F ?? E8 ?? ?? ?? ?? 4C 8B 4C 24 ?? 44 8D 43 ?? 48 8B C8 8B D7 48 8B F0 44 8B F7 E8 ?? ?? ?? ?? 48 8B 4C 24 ?? E8 ?? ?? ??}

	condition:
		( uint16( 0 ) == 0x4d5a and filesize < 2MB and pe.characteristics & pe.DLL and 1 of ( $x* ) ) or all of ( $opa* )
}

Strings (4 patterns)

Identifier	Type	Value
$x1	text	"%s\\config\\TxR\\%s.TxR.0.regtrans-ms"
$xop	hex	{D1 E8 33 C3 D1 EB A8 01 74 ?? 81 F3 25 A3 87 DE D1 E8 33 C3 D1 EB A8 01 74 ?? 81 F3 25 A3 87 DE D1 E8 33 C3 D1 EB A8 01 74 ?? 81 F3 25 A3 87 DE D1 E8 33 C3 D1 …
$opa1	hex	{48 89 44 24 ?? 45 33 C9 45 33 C0 33 D2 89 5C 24 ?? 48 89 74 24 ?? 48 89 5C 24 ?? 89 7C 24 ?? FF 15 ?? ?? ?? ?? 85 C0 74 ?? 48 8B 4C 24 ?? 4C 8D 4C 24 ?? 44 8D …
$opa2	hex	{48 89 B4 24 ?? ?? ?? ?? 44 8D 43 ?? 33 D2 48 89 BC 24 ?? ?? ?? ?? 4C 89 B4 24 ?? ?? ?? ?? E8 ?? ?? ?? ?? 48 8B 4C 24 ?? E8 ?? ?? ?? ?? 48 8B 4C 24 ?? 45 33 C0 …

Condition

( uint16( 0 ) == 0x4d5a and filesize < 2MB and pe.characteristics & pe.DLL and 1 of ( $x* ) ) or all of ( $opa* )

In plain words (Heuristic)

The file must be smaller than 2MB (a cheap guard that skips large files).
All patterns in ( $opa* ) must match.
At least 1 patterns in ( $x* ) must match.
Uses the pe module.
Requires a DLL.

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References

https://github.com/SEKOIA-IO/Community

Sample hashes

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

97b95b4a5461f950e712b82783930cb2a152ec0288c00a977983ca7788342df7
beb775af5196f30e0ee021790a4978ca7a7ac2a7cf970a5a620ffeb89cc60b2c

Licence & attribution

Author: Sekoia.io

Source repository: SEKOIA.IO Community @ a438a5901a

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: 947d4ee3-79fa-450b-8482-beafe607baae

Metadata

version	1.0
classification	TLP:CLEAR

Tags:FILE

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