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YARA · Signature Base (Florian Roth / Nextron)

SIGNATURE_BASE_MAL_APT_NK_Andariel_Grease2

Detects the Grease2 malware family used by Andariel

MalwareSignature Base (Florian Roth / Nextron)Detection Rule License 1.1Compiles with YARA-X
Author
CISA.gov (modified by Florian Roth, Nextron Systems)
Date
2024-07-25
Modified
2024-07-26
Score / Quality
80 / 85

What this rule detects

Detects the Grease2 malware family used by Andariel

Targets: Windows PE.

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

Summary generated from the rule's metadata and condition.

Rule source

Download .yar
mal-apt-nk-andariel-grease2.yarDetection Rule License 1.1
rule SIGNATURE_BASE_MAL_APT_NK_Andariel_Grease2 : FILE
{
	meta:
		description = "Detects the Grease2 malware family used by Andariel"
		author = "CISA.gov (modified by Florian Roth, Nextron Systems)"
		id = "4defbe08-b3c6-5ab9-9a57-cec57ff42d9a"
		date = "2024-07-25"
		modified = "2024-07-26"
		reference = "https://www.cisa.gov/news-events/cybersecurity-advisories/aa24-207a"
		source_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/apt_nk_andariel_jul24.yar#L330-L351"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		logic_hash = "138fc915206e0c2834090ebc0a808913488121d51c17de3dbfadcb4099fbfa2f"
		score = 80
		quality = 85
		tags = "FILE"

	strings:
		$str_rdpconf = "emp\\RDPConf.exe"
		$str_rdpwinst = "emp\\RDPWInst.exe"
		$str_net_user = "net user"
		$str_admins_add = "net localgroup administrators"

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

Strings (4 patterns)

IdentifierTypeValueModifiers
$str_rdpconftext"emp\\RDPConf.exe"
$str_rdpwinsttext"emp\\RDPWInst.exe"
$str_net_usertext"net user"
$str_admins_addtext"net localgroup administrators"

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

Licence & attribution

Author: CISA.gov (modified by 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: 4defbe08-b3c6-5ab9-9a57-cec57ff42d9a

Tags:FILE

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