YARA · Signature Base (Florian Roth / Nextron)

SIGNATURE_BASE_APT_UNC2447_BAT_Runner_May21_1

Detects Batch script runners 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: 2023-01-07
Score / Quality: 75 / 85

What this rule detects

Detects Batch script runners from UNC2447 campaign

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

Summary generated from the rule's metadata and condition.

Rule source

Download .yar

apt-unc2447-bat-runner-may21-1.yarDetection Rule License 1.1

rule SIGNATURE_BASE_APT_UNC2447_BAT_Runner_May21_1 : FILE
{
	meta:
		description = "Detects Batch script runners from UNC2447 campaign"
		author = "Florian Roth (Nextron Systems)"
		id = "0bacd4f7-421a-570f-9f74-5a19ab806dd0"
		date = "2021-05-01"
		modified = "2023-01-07"
		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#L121-L135"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		hash = "ccacf4658ae778d02e4e55cd161b5a0772eb8b8eee62fed34e2d8f11db2cc4bc"
		logic_hash = "f9872327f648e4421aa40ca3ce55df5d3eb5e8c5bc718ff62a3d4adac79217eb"
		score = 75
		quality = 85
		tags = "FILE"

	strings:
		$x1 = "powershell.exe -c \"[System.Text.Encoding]::UTF8.GetString([System.Convert]::FromBase64String([IO.File]::" ascii
		$x2 = "wwansvc.txt')))\" | powershell.exe -" ascii

	condition:
		filesize < 5000KB and 1 of them
}

Strings (2 patterns)

Identifier	Type	Value	Modifiers
$x1	text	"powershell.exe -c \"[System.Text.Encoding]::UTF8.GetString([System.Convert]::FromBase64String([IO.File]::"	ascii
$x2	text	"wwansvc.txt')))\" \| powershell.exe -"	ascii

Condition

filesize < 5000KB and 1 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 the rule must match.

Test this rule in your browser

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

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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).

ccacf4658ae778d02e4e55cd161b5a0772eb8b8eee62fed34e2d8f11db2cc4bc

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: 0bacd4f7-421a-570f-9f74-5a19ab806dd0

Tags:FILE

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