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SEKOIA_Apt_Mustang_Panda_Toneshell

Detect the TONESHELL implant used by Mustang Panda from specific functions

APT / threat actorSEKOIA.IO CommunityDetection Rule License 1.1Compiles with YARA-X (with warnings)
Author
Sekoia.io
Date
2022-11-28
Modified
2024-12-19
Score / Quality
75 / 80

What this rule detects

Detect the TONESHELL implant used by Mustang Panda from specific functions

Targets: Windows PE.

It defines 4 patterns (0 text, 4 hex, 0 regex). 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.

apt-mustang-panda-toneshell.yarDetection Rule License 1.1
import "pe"
import "hash"

rule SEKOIA_Apt_Mustang_Panda_Toneshell : FILE
{
	meta:
		description = "Detect the TONESHELL implant used by Mustang Panda from specific functions"
		author = "Sekoia.io"
		id = "bf7c68a9-dddc-494a-a603-c2311ed712a4"
		date = "2022-11-28"
		modified = "2024-12-19"
		reference = "https://github.com/SEKOIA-IO/Community"
		source_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/yara_rules/apt_mustang_panda_toneshell.yar#L4-L160"
		license_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/LICENSE.md"
		logic_hash = "192fb01817cc6361062999cf539c51616d1755a5cd8e9d6e37bee6f6d04b0721"
		score = 75
		quality = 80
		tags = "FILE"
		version = "1.0"
		classification = "TLP:CLEAR"

	strings:
		$func1 = {
        55
        89 E5
        64 A1 18 00 00 00
        A3 ?? ?? ?? ??
        5D
        C3
        }
		$func2 = {
        55
        89 E5
        50
        8B 45 ??
        8B 45 ??
        8B 45 ??
        8B 45 ??
        89 45 ??
        8B 45 ??
        89 C1
        83 C1 FF
        89 4D ??
        83 F8 00
        0F 84 ?? ?? ?? ??
        8B 45 ??
        8A 08
        8B 45 ??
        88 08
        8B 45 ??
        83 C0 01
        89 45 ??
        8B 45 ??
        83 C0 01
        89 45 ??
        E9 ?? ?? ?? ??
        8B 45 ??
        83 C4 04
        5D
        C3
        }
		$decryption_routine1 = {
        8B 45 ??
        C7 45 ?? 00 00 00 00
        83 7D ?? 20
        0F 8D ?? ?? ?? ??
        8B 45 ??
        8B 4D ??
        0F BE 04 08
        83 F0 ??
        88 C2
        8B 45 ??
        8B 4D ??
        88 14 08
        8B 45 ??
        83 C0 01
        89 45 ??
        E9 ?? ?? ?? ??
        83 C4 04
        }
		$decryption_routine2 = {
        55
        89 E5
        83 EC 08
        8B 45 ??
        8B 45 ??
        8B 45 ??
        8B 45 ??
        C7 45 ?? 00 00 00 00
        C7 45 ?? 00 00 00 00
        8B 45 ??
        3B 45 ??
        0F 8D ?? ?? ?? ??
        8B 45 ??
        8B 4D ??
        0F BE 04 08
        8B 4D ??
        8B 55 ??
        0F BE 0C 11
        31 C8
        88 C2
        8B 45 ??
        8B 4D ??
        88 14 08
        8B 45 ??
        8B 4D ??
        83 E9 01
        39 C8
        0F 85 ?? ?? ?? ??
        C7 45 ?? 00 00 00 00
        E9 ?? ?? ?? ??
        8B 45 ??
        83 C0 01
        89 45 ??
        8B 45 ??
        83 C0 01
        89 45 ??
        E9 ?? ?? ?? ??
        83 C4 08
        5D
        C3
        }

	condition:
		uint16be( 0 ) == 0x4d5a and filesize < 8MB and for all i in ( 0 .. pe.number_of_sections -1 ) : ( hash.md5 ( pe.sections [ i ] . raw_data_offset , pe.sections [ i ] . raw_data_size ) != "69f400d3ff4679294e63fb8a8ca97dbb" ) and 3 of them and true
}

Strings (4 patterns)

IdentifierTypeValueModifiers
$func1hex{ 55 89 E5 64 A1 18 00 00 00 A3 ?? ?? ?? ?? 5D C3 }
$func2hex{ 55 89 E5 50 8B 45 ?? 8B 45 ?? 8B 45 ?? 8B 45 ?? 89 45 ?? 8B 45 ?? 89 C1 …
$decryption_routine1hex{ 8B 45 ?? C7 45 ?? 00 00 00 00 83 7D ?? 20 0F 8D ?? ?? ?? ?? 8B 45 ?? 8B 4D ?? 0F BE 04 08 83 F …
$decryption_routine2hex{ 55 89 E5 83 EC 08 8B 45 ?? 8B 45 ?? 8B 45 ?? 8B 45 ?? C7 45 ?? 00 00 00 00 C7 45 ?? 00 …

Condition

uint16be( 0 ) == 0x4d5a and filesize < 8MB and for all i in ( 0 .. pe.number_of_sections -1 ) : ( hash.md5 ( pe.sections [ i ] . raw_data_offset , pe.sections [ i ] . raw_data_size ) != "69f400d3ff4679294e63fb8a8ca97dbb" ) and 3 of them and true

In plain words (Heuristic)

  • The file must start with “MZ” — a Windows executable (PE).
  • The file must be smaller than 8MB (a cheap guard that skips large files).
  • At least 3 patterns in the rule must match.
  • 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

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: bf7c68a9-dddc-494a-a603-c2311ed712a4

Metadata

version1.0
classificationTLP:CLEAR

Tags:FILE

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