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SEKOIA_Implant_Win_Graphiron_Downloader

Detect the downloader of Graphiron

MalwareSEKOIA.IO CommunityDetection Rule License 1.1Compiles with YARA-X (with warnings)
Author
Sekoia.io
Date
2023-02-10
Modified
2024-12-19
Score / Quality
75 / 80

What this rule detects

Detect the downloader of Graphiron

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

Download .yar

Includes the imports needed to compile it on its own.

implant-win-graphiron-downloader.yarDetection Rule License 1.1
import "pe"
import "hash"

rule SEKOIA_Implant_Win_Graphiron_Downloader : FILE
{
	meta:
		description = "Detect the downloader of Graphiron"
		author = "Sekoia.io"
		id = "c50c4bd2-3828-43bf-b45c-8e911c298536"
		date = "2023-02-10"
		modified = "2024-12-19"
		reference = "https://github.com/SEKOIA-IO/Community"
		source_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/yara_rules/implant_win_graphiron_downloader.yar#L4-L22"
		license_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/LICENSE.md"
		hash = "0d0a675516f1ff9247f74df31e90f06b0fea160953e5e3bada5d1c8304cfbe63"
		hash = "878450da2e44f5c89ce1af91479b9a9491fe45211fee312354dfe69e967622db"
		logic_hash = "f0aa0541cbf3f93ee136cf3235a4935f1c0588b5cdb21203abee9f61baf3f4f2"
		score = 75
		quality = 80
		tags = "FILE"
		version = "1.0"
		classification = "TLP:CLEAR"

	condition:
		for any i in ( 0 .. pe.number_of_sections -1 ) : ( hash.md5 ( pe.sections [ i ] . raw_data_offset , pe.sections [ i ] . raw_data_size ) == "1b614f8d813125f56d2e772ed0ca5dae" or hash.md5 ( pe.sections [ i ] . raw_data_offset , pe.sections [ i ] . raw_data_size ) == "5c6496d33de5a35bd38ddb12d8b42e03" ) and filesize > 3MB and filesize < 6MB
}

Condition

for any i in ( 0 .. pe.number_of_sections -1 ) : ( hash.md5 ( pe.sections [ i ] . raw_data_offset , pe.sections [ i ] . raw_data_size ) == "1b614f8d813125f56d2e772ed0ca5dae" or hash.md5 ( pe.sections [ i ] . raw_data_offset , pe.sections [ i ] . raw_data_size ) == "5c6496d33de5a35bd38ddb12d8b42e03" ) and filesize > 3MB and filesize < 6MB

In plain words (Heuristic)

  • The file must be smaller than 6MB (a cheap guard that skips large files).
  • The file must be larger than 3MB.
  • A for-loop checks a property over several matches or items.
  • Uses the pe module.
  • Uses the hash module.
  • Compares a hash of the file or a part of it.
  • Checks PE sections (names, count or properties).

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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).

  • 0d0a675516f1ff9247f74df31e90f06b0fea160953e5e3bada5d1c8304cfbe63
  • 878450da2e44f5c89ce1af91479b9a9491fe45211fee312354dfe69e967622db

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: c50c4bd2-3828-43bf-b45c-8e911c298536

Metadata

version1.0
classificationTLP:CLEAR

Tags:FILE

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