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YARA · Signature Base (Florian Roth / Nextron)

SIGNATURE_BASE_APT28_Skinnyboy_Dropper_1

Detects APT28 SkinnyBoy droppers

MalwareSkinnyboySignature Base (Florian Roth / Nextron)Detection Rule License 1.1Compiles with YARA-X
Author
Cluster25
Date
2021-05-24
Modified
2023-12-05
Score / Quality
75 / 85

What this rule detects

Detects APT28 SkinnyBoy droppers

Associated malware family: Skinnyboy.

Targets: Windows PE.

It defines 3 patterns (1 text, 2 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

Download .yar
apt28-skinnyboy-dropper-1.yarDetection Rule License 1.1
rule SIGNATURE_BASE_APT28_Skinnyboy_Dropper_1 : RUSSIA FILE
{
	meta:
		description = "Detects APT28 SkinnyBoy droppers"
		author = "Cluster25"
		id = "ed0b2d2b-f820-57b5-9654-c24734d81996"
		date = "2021-05-24"
		modified = "2023-12-05"
		reference = "https://cluster25.io/wp-content/uploads/2021/05/2021-05_FancyBear.pdf"
		source_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/apt_apt28.yar#L103-L118"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		hash = "12331809c3e03d84498f428a37a28cf6cbb1dafe98c36463593ad12898c588c9"
		logic_hash = "9e29ed985fac8701f72f0860fe101272c3c3342ef6857e30d32f5fea14822945"
		score = 75
		quality = 85
		tags = "RUSSIA, FILE"

	strings:
		$ = "cmd /c DEL " ascii
		$ = {8a 08 40 84 c9 75 f9}
		$ = {0f b7 84 0d fc fe ff ff 66 31 84 0d fc fd ff ff}

	condition:
		( uint16( 0 ) == 0x5A4D and all of them )
}

Strings (3 patterns)

IdentifierTypeValueModifiers
$text"cmd /c DEL "ascii
$hex{8a 08 40 84 c9 75 f9}
$hex{0f b7 84 0d fc fe ff ff 66 31 84 0d fc fd ff ff}

Condition

( uint16( 0 ) == 0x5A4D and all of them )

In plain words (Heuristic)

  • The file must start with “MZ” — a Windows executable (PE).
  • All patterns in the rule must match.

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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).

  • 12331809c3e03d84498f428a37a28cf6cbb1dafe98c36463593ad12898c588c9

Licence & attribution

Author: Cluster25

Source repository: Signature Base (Florian Roth / Nextron) @ 94a1c48d7a

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: ed0b2d2b-f820-57b5-9654-c24734d81996

Tags:RUSSIAFILE

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