YARA · Signature Base (Florian Roth / Nextron)

SIGNATURE_BASE_APT_UNC2447_PS1_WARPRISM_May21_1

Detects WARPRISM PowerShell samples from UNC2447 campaign

APT / threat actorSignature Base (Florian Roth / Nextron)Detection Rule License 1.1Compiles with YARA-X

Author: Florian Roth (Nextron Systems)
Date: 2021-05-01
Modified: 2023-12-05
Score / Quality: 75 / 85

What this rule detects

Detects WARPRISM PowerShell samples from UNC2447 campaign

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

Summary generated from the rule's metadata and condition.

Rule source

Download .yar

apt-unc2447-ps1-warprism-may21-1.yarDetection Rule License 1.1

rule SIGNATURE_BASE_APT_UNC2447_PS1_WARPRISM_May21_1 : FILE
{
	meta:
		description = "Detects WARPRISM PowerShell samples from UNC2447 campaign"
		author = "Florian Roth (Nextron Systems)"
		id = "fa389a45-3b31-5a84-9882-49fd6ee8cac5"
		date = "2021-05-01"
		modified = "2023-12-05"
		reference = "https://www.fireeye.com/blog/threat-research/2021/04/unc2447-sombrat-and-fivehands-ransomware-sophisticated-financial-threat.html"
		source_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/apt_unc2447_sombrat.yar#L101-L119"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		hash = "3090bff3d16b0b150444c3bfb196229ba0ab0b6b826fa306803de0192beddb80"
		hash = "63ba6db8c81c60dd9f1a0c7c4a4c51e2e56883f063509ed7b543ad7651fd8806"
		hash = "b41a303a4caa71fa260dd601a796033d8bfebcaa6bd9dfd7ad956fac5229a735"
		logic_hash = "09abac2be0f12d31dabfdae9e8a148a28887a2a5df003c7bcb56ba45f1c6a62c"
		score = 75
		quality = 85
		tags = "FILE"

	strings:
		$x1 = "if ($MyInvocation.MyCommand.Path -match '\\S') {" ascii fullword
		$s1 = "[DllImport(\"kernel32.dll\")]public static extern IntPtr VirtualAlloc(IntPtr " ascii wide
		$s2 = "[Runtime.InteropServices.Marshal]::Copy($" ascii wide
		$s3 = "[System.Diagnostics.Process]::Start((-join(" ascii wide

	condition:
		filesize < 5000KB and 1 of ( $x* ) or 2 of them
}

Strings (4 patterns)

Identifier	Type	Value	Modifiers
$x1	text	"if ($MyInvocation.MyCommand.Path -match '\\S') {"	ascii fullword
$s1	text	"[DllImport(\"kernel32.dll\")]public static extern IntPtr VirtualAlloc(IntPtr "	ascii wide
$s2	text	"[Runtime.InteropServices.Marshal]::Copy($"	ascii wide
$s3	text	"[System.Diagnostics.Process]::Start((-join("	ascii wide

Condition

filesize < 5000KB and 1 of ( $x* ) or 2 of them

In plain words (Heuristic)

The file must be smaller than 5000KB (a cheap guard that skips large files).
At least 1 patterns in ( $x* ) must match.
At least 2 patterns in the rule must match.

Test this rule in your browser

Drop a file to scan it with this rule using YARA-X compiled to WebAssembly. Nothing is uploaded.

Drop a file here or click to chooseScanned locally with YARA-X. Files up to 200 MB.

Open in editor

References

https://www.fireeye.com/blog/threat-research/2021/04/unc2447-sombrat-and-fivehands-ransomware-sophisticated-financial-threat.html

Sample hashes

Hashes of samples the author lists in the rule's meta (look them up in your threat-intelligence platform).

3090bff3d16b0b150444c3bfb196229ba0ab0b6b826fa306803de0192beddb80
63ba6db8c81c60dd9f1a0c7c4a4c51e2e56883f063509ed7b543ad7651fd8806
b41a303a4caa71fa260dd601a796033d8bfebcaa6bd9dfd7ad956fac5229a735

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: fa389a45-3b31-5a84-9882-49fd6ee8cac5

Tags:FILE

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