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YARA · Signature Base (Florian Roth / Nextron)

SIGNATURE_BASE_APT_MAL_Win_Decrok

The DECROK malware family, which uses the victim's hostname to decrypt and execute an embedded payload.

APT / threat actorSignature Base (Florian Roth / Nextron)BSD 2-Clause LicenseCompiles with YARA-X
Author
threatintel@volexity.com
Date
2021-06-23
Modified
2023-12-05
Score / Quality
75 / 85

What this rule detects

The DECROK malware family, which uses the victim's hostname to decrypt and execute an embedded payload.

It defines 4 patterns (2 text, 2 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

Download .yar
apt-mal-win-decrok.yarBSD 2-Clause License
rule SIGNATURE_BASE_APT_MAL_Win_Decrok : INKYSQUID
{
	meta:
		description = "The DECROK malware family, which uses the victim's hostname to decrypt and execute an embedded payload."
		author = "threatintel@volexity.com"
		id = "dc83843d-fd2a-52f1-82e8-8e36b135a0c5"
		date = "2021-06-23"
		modified = "2023-12-05"
		reference = "https://www.volexity.com/blog/2021/08/24/north-korean-bluelight-special-inkysquid-deploys-rokrat/"
		source_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/apt_nk_inkysquid.yar#L61-L82"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		hash = "6a452d088d60113f623b852f33f8f9acf0d4197af29781f889613fed38f57855"
		logic_hash = "47fa03e95ac17ba7195858cd63b1769e5d56ab8a5edf872b345989b767050b87"
		score = 75
		quality = 85
		tags = "INKYSQUID"
		license = "See license at https://github.com/volexity/threat-intel/LICENSE.txt"

	strings:
		$v1 = {C7 ?? ?? ?? 01 23 45 67 [2-20] C7 ?? ?? ?? 89 AB CD EF C7 ?? ?? ?? FE DC BA 98}
		$av1 = "Select * From AntiVirusProduct" wide
		$av2 = "root\\SecurityCenter2" wide
		$funcformat = { 25 30 32 78 [0-10] 43 72 65 61 74 65 54 68 72 65 61 64 }

	condition:
		all of them
}

Strings (4 patterns)

IdentifierTypeValueModifiers
$v1hex{C7 ?? ?? ?? 01 23 45 67 [2-20] C7 ?? ?? ?? 89 AB CD EF C7 ?? ?? ?? FE DC BA 98}
$av1text"Select * From AntiVirusProduct"wide
$av2text"root\\SecurityCenter2"wide
$funcformathex{ 25 30 32 78 [0-10] 43 72 65 61 74 65 54 68 72 65 61 64 }

Condition

all of them

In plain words (Heuristic)

  • 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).

  • 6a452d088d60113f623b852f33f8f9acf0d4197af29781f889613fed38f57855

Licence & attribution

Author: threatintel@volexity.com

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

Licence: BSD 2-Clause License (stated in the rule's own meta)

“See license at https://github.com/volexity/threat-intel/LICENSE.txt”

Original rule

Mirrored via YARA Forge 20260927, which prefixes rule names with the source and adds normalised meta fields.

Rule id: dc83843d-fd2a-52f1-82e8-8e36b135a0c5

Tags:INKYSQUID

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