Skip to content

YARA · SEKOIA.IO Community

SEKOIA_Backdoor_Win_Winordll64

Detect the WinorDLL64 backdoor

MalwareWinordll64SEKOIA.IO CommunityDetection Rule License 1.1Compiles with YARA-X (with warnings)
Author
Sekoia.io
Date
2023-02-24
Modified
2024-12-19
Score / Quality
75 / 80

What this rule detects

Detect the WinorDLL64 backdoor

Associated malware family: Winordll64.

Targets: Windows PE.

It has no patterns: the condition alone decides (modules, file properties or other rules). YARA modules used: pe, hash.

YARA-X says: warning[deprecated_field]: field `number_of_sections` is deprecated

Summary generated from the rule's metadata and condition.

Rule source

Includes the imports needed to compile it on its own.

backdoor-win-winordll64.yarDetection Rule License 1.1
import "pe"
import "hash"

rule SEKOIA_Backdoor_Win_Winordll64
{
	meta:
		description = "Detect the WinorDLL64 backdoor"
		author = "Sekoia.io"
		id = "86a32538-bc69-47ea-9842-4af360588c27"
		date = "2023-02-24"
		modified = "2024-12-19"
		reference = "https://github.com/SEKOIA-IO/Community"
		source_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/yara_rules/backdoor_win_winordll64.yar#L4-L23"
		license_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/LICENSE.md"
		logic_hash = "30e6f01f30d6ef11c75e133d309cebc87b69ede8eb38aa14d237760e99b52c54"
		score = 75
		quality = 80
		tags = ""
		version = "1.0"
		classification = "TLP:CLEAR"

	condition:
		hash.md5( pe.rich_signature.clear_data ) == "d16713cbfe04151b3a9e832c8afd55df" or for any i in ( 0 .. pe.number_of_sections -1 ) : ( hash.md5 ( pe.sections [ i ] . raw_data_offset , pe.sections [ i ] . raw_data_size ) == "3f638774c2565594029fb52ceb67db7a" or hash.md5 ( pe.sections [ i ] . raw_data_offset , pe.sections [ i ] . raw_data_size ) == "f9416bfb43b2c70837927e43e7591a2a" or hash.md5 ( pe.sections [ i ] . raw_data_offset , pe.sections [ i ] . raw_data_size ) == "6eede2cebaef39eec5bd1c24c809e3dc" or hash.md5 ( pe.sections [ i ] . raw_data_offset , pe.sections [ i ] . raw_data_size ) == "1177658fb0469cd5982102c9f3cd2eea" or hash.md5 ( pe.sections [ i ] . raw_data_offset , pe.sections [ i ] . raw_data_size ) == "658d877d1bf0d2928b2c3efec9ec06cf" ) or pe.imphash ( ) == "d6b6f8cdffb06f469e06c7af9639897c"
}

Condition

hash.md5( pe.rich_signature.clear_data ) == "d16713cbfe04151b3a9e832c8afd55df" or for any i in ( 0 .. pe.number_of_sections -1 ) : ( hash.md5 ( pe.sections [ i ] . raw_data_offset , pe.sections [ i ] . raw_data_size ) == "3f638774c2565594029fb52ceb67db7a" or hash.md5 ( pe.sections [ i ] . raw_data_offset , pe.sections [ i ] . raw_data_size ) == "f9416bfb43b2c70837927e43e7591a2a" or hash.md5 ( pe.sections [ i ] . raw_data_offset , pe.sections [ i ] . raw_data_size ) == "6eede2cebaef39eec5bd1c24c809e3dc" or hash.md5 ( pe.sections [ i ] . raw_data_offset , pe.sections [ i ] . raw_data_size ) == "1177658fb0469cd5982102c9f3cd2eea" or hash.md5 ( pe.sections [ i ] . raw_data_offset , pe.sections [ i ] . raw_data_size ) == "658d877d1bf0d2928b2c3efec9ec06cf" ) or pe.imphash ( ) == "d6b6f8cdffb06f469e06c7af9639897c"

In plain words (Heuristic)

  • A for-loop checks a property over several matches or items.
  • Uses the hash module.
  • Uses the pe module.
  • Compares a hash of the file or a part of it.
  • Checks the PE import hash (imphash).
  • Checks PE sections (names, count or properties).

Test this rule in your browser

Drop a file to scan it with this rule using YARA-X compiled to WebAssembly. Nothing is uploaded.

Drop a file here or click to chooseScanned locally with YARA-X. Files up to 200 MB.

Open in editor

References

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: 86a32538-bc69-47ea-9842-4af360588c27

Metadata

version1.0
classificationTLP:CLEAR