YARA · SEKOIA.IO Community

SEKOIA_Apt_Gelsemium_Wolfsbane_Backdoor

Detects Gelsemium's WolfsBane backdoor

APT / threat actorSEKOIA.IO CommunityDetection Rule License 1.1Compiles with YARA-X

Author: Sekoia.io
Date: 2024-11-22
Modified: 2024-12-19
Score / Quality: 75 / 80

What this rule detects

Detects Gelsemium's WolfsBane backdoor

Targets: Linux ELF.

It defines 6 patterns (6 text, 0 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

Download .yar

apt-gelsemium-wolfsbane-backdoor.yarDetection Rule License 1.1

rule SEKOIA_Apt_Gelsemium_Wolfsbane_Backdoor : FILE
{
	meta:
		description = "Detects Gelsemium's WolfsBane backdoor"
		author = "Sekoia.io"
		id = "db2ad5a4-b592-4646-a385-c668bb2ea090"
		date = "2024-11-22"
		modified = "2024-12-19"
		reference = "https://github.com/SEKOIA-IO/Community"
		source_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/yara_rules/apt_gelsemium_wolfsbane_backdoor.yar#L1-L24"
		license_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/LICENSE.md"
		hash = "1418fe9a743226b9661a2b6decb19db0"
		logic_hash = "97d5076ca4c204a2e2276fd250d64bc140da1f2c8dec9996db7a622385f2c0ac"
		score = 75
		quality = 80
		tags = "FILE"
		version = "1.0"
		classification = "TLP:CLEAR"

	strings:
		$ = "udp_session"
		$ = "session_interface"
		$ = "plugin_persist"
		$ = "Udp.cpp"
		$ = "ikcp.c"
		$ = "' %s 2>/dev/null"

	condition:
		uint32be( 0 ) == 0x7f454c46 and filesize > 3MB and filesize < 4MB and 4 of them
}

Strings (6 patterns)

Identifier	Type	Value
$	text	"udp_session"
$	text	"session_interface"
$	text	"plugin_persist"
$	text	"Udp.cpp"
$	text	"ikcp.c"
$	text	"' %s 2>/dev/null"

Condition

uint32be( 0 ) == 0x7f454c46 and filesize > 3MB and filesize < 4MB and 4 of them

In plain words (Heuristic)

The file must start with the ELF header — a Linux/Unix executable.
The file must be smaller than 4MB (a cheap guard that skips large files).
The file must be larger than 3MB.
At least 4 patterns in the rule must match.

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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).

1418fe9a743226b9661a2b6decb19db0

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: db2ad5a4-b592-4646-a385-c668bb2ea090

Metadata

version	1.0
classification	TLP:CLEAR

Tags:FILE

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