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YARA · Signature Base (Florian Roth / Nextron)

SIGNATURE_BASE_APT_CN_APT27_Compromised_Certficate_Jan22_1

Detects compromised certifcates used by APT27 malware

APT / threat actorSignature Base (Florian Roth / Nextron)Detection Rule License 1.1Compiles with YARA-X (with warnings)
Author
Florian Roth (Nextron Systems)
Date
2022-01-29
Modified
2023-12-05
Score / Quality
80 / 85

What this rule detects

Detects compromised certifcates used by APT27 malware

Targets: Windows PE.

It has no patterns: the condition alone decides (modules, file properties or other rules). YARA modules used: pe.

YARA-X says: warning[deprecated_field]: field `number_of_signatures` 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-cn-apt27-compromised-certficate-jan22-1.yarDetection Rule License 1.1
import "pe"

rule SIGNATURE_BASE_APT_CN_APT27_Compromised_Certficate_Jan22_1
{
	meta:
		description = "Detects compromised certifcates used by APT27 malware"
		author = "Florian Roth (Nextron Systems)"
		id = "f2f015af-219d-51ab-9529-01687a879ebb"
		date = "2022-01-29"
		modified = "2023-12-05"
		reference = "https://www.verfassungsschutz.de/SharedDocs/publikationen/DE/cyberabwehr/2022-01-bfv-cyber-brief.pdf"
		source_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/apt_apt27_hyperbro.yar#L21-L34"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		logic_hash = "94a40d55936fc341eaba5e1accc8bfe3a401114298e7a3cc4d5c64af36eadf9e"
		score = 80
		quality = 85
		tags = ""

	condition:
		for any i in ( 0 .. pe.number_of_signatures ) : ( pe.signatures [ i ] . issuer contains "DigiCert SHA2 Assured ID Code Signing CA" and pe.signatures [ i ] . serial == "08:68:70:51:50:f1:cf:c1:fc:c3:fc:91:a4:49:49:a6" )
}

Condition

for any i in ( 0 .. pe.number_of_signatures ) : ( pe.signatures [ i ] . issuer contains "DigiCert SHA2 Assured ID Code Signing CA" and pe.signatures [ i ] . serial == "08:68:70:51:50:f1:cf:c1:fc:c3:fc:91:a4:49:49:a6" )

In plain words (Heuristic)

  • A for-loop checks a property over several matches or items.
  • Uses the pe module.
  • Checks the Authenticode signature.

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References

Licence & attribution

Author: Florian Roth (Nextron Systems)

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: f2f015af-219d-51ab-9529-01687a879ebb

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