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SEKOIA_Apt_Apt28_Susp_Graphite_Downloader

Matches the routine which decrypts the RSA key blob in the Graphite downloader

APT / threat actorGraphiteSEKOIA.IO CommunityDetection Rule License 1.1Compiles with YARA-X
Author
Sekoia.io
Date
2022-01-26
Modified
2024-12-19
Score / Quality
65 / 80

What this rule detects

Matches the routine which decrypts the RSA key blob in the Graphite downloader

Associated malware family: Graphite.

Targets: Windows PE.

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

Summary generated from the rule's metadata and condition.

Rule source

Includes the imports needed to compile it on its own.

apt-apt28-susp-graphite-downloader.yarDetection Rule License 1.1
import "pe"

rule SEKOIA_Apt_Apt28_Susp_Graphite_Downloader : FILE
{
	meta:
		description = "Matches the routine which decrypts the RSA key blob in the Graphite downloader"
		author = "Sekoia.io"
		id = "9c9da5fe-ffd6-4c45-8ce1-9a6cf4fa2fda"
		date = "2022-01-26"
		modified = "2024-12-19"
		reference = "https://github.com/SEKOIA-IO/Community"
		source_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/yara_rules/apt_apt28_susp_graphite_downloader.yar#L3-L26"
		license_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/LICENSE.md"
		logic_hash = "ca5aa7ea995aca9003fd98da2fba7bbec1e049d979a6b05e07b80876bab5a1c9"
		score = 65
		quality = 80
		tags = "FILE"
		version = "1.0"
		classification = "TLP:CLEAR"

	strings:
		$gen = { 33 D2
        8B C1
        6A ??
        5E
        F7 F6
        8A 82 ?? ?? ?? ??
        30 81 ?? ?? ?? ??
        41
        81 F9 94 04 00 00
        72 E2 }

	condition:
		uint16be( 0 ) == 0x4d5a and $gen and pe.number_of_exports == 1
}

Strings (1 patterns)

IdentifierTypeValueModifiers
$genhex{ 33 D2 8B C1 6A ?? 5E F7 F6 8A 82 ?? ?? ?? ?? 30 81 ?? ?? ?? ?? 41 81 F9 94 04 00 00 72 …

Condition

uint16be( 0 ) == 0x4d5a and $gen and pe.number_of_exports == 1

In plain words (Heuristic)

  • The file must start with “MZ” — a Windows executable (PE).
  • Pattern $gen must be present.
  • Uses the pe module.
  • Checks exported functions or the DLL name.

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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: 9c9da5fe-ffd6-4c45-8ce1-9a6cf4fa2fda

Metadata

version1.0
classificationTLP:CLEAR

Tags:FILE

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