YARA · Signature Base (Florian Roth / Nextron)

SIGNATURE_BASE_APT_APT29_NOBELIUM_Boombox_May21_2

Detects BoomBox malware used by APT29 / NOBELIUM

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

Author: Florian Roth (Nextron Systems)
Date: 2021-05-29
Modified: 2025-03-21
Score / Quality: 75 / 85

What this rule detects

Detects BoomBox malware used by APT29 / NOBELIUM

Targets: Windows PE.

It defines 10 patterns (7 text, 3 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

Download .yar

apt-apt29-nobelium-boombox-may21-2.yarDetection Rule License 1.1

rule SIGNATURE_BASE_APT_APT29_NOBELIUM_Boombox_May21_2 : FILE
{
	meta:
		description = "Detects BoomBox malware used by APT29 / NOBELIUM"
		author = "Florian Roth (Nextron Systems)"
		id = "a4144c00-48b2-5520-b773-5d0a5de95fb1"
		date = "2021-05-29"
		modified = "2025-03-21"
		reference = "https://www.microsoft.com/security/blog/2021/05/28/breaking-down-nobeliums-latest-early-stage-toolset/"
		source_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/apt_apt29_nobelium_may21.yar#L206-L234"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		hash = "0acb884f2f4cfa75b726cb8290b20328c8ddbcd49f95a1d761b7d131b95bafec"
		hash = "8199f309478e8ed3f03f75e7574a3e9bce09b4423bd7eb08bb5bff03af2b7c27"
		hash = "cf1d992f776421f72eabc31d5afc2f2067ae856f1c9c1d6dc643a67cb9349d8c"
		logic_hash = "2a3829e704af2464639d07e8e7952669281e20cf2a7ac487d5d1eee021d08b35"
		score = 75
		quality = 85
		tags = "FILE"

	strings:
		$x1 = "\\Microsoft\\NativeCache\\NativeCacheSvc.dll" wide
		$x2 = "\\NativeCacheSvc.dll _configNativeCache" wide
		$a1 = "/content.dropboxapi.com" wide fullword
		$s1 = "rundll32.exe {0} {1}" wide fullword
		$s2 = "\\\\CertPKIProvider.dll" wide
		$s3 = "/tmp/readme.pdf" wide
		$s4 = "temp/[^\"]*)\"" wide fullword
		$op1 = { 00 78 00 2d 00 41 00 50 00 49 00 2d 00 41 00 72 00 67 00 01 2f 4f 00 72 00 }
		$op2 = { 25 72 98 01 00 70 6f 34 00 00 0a 25 6f 35 00 00 0a 72 71 02 00 70 72 }
		$op3 = { 4d 05 20 00 12 80 91 04 20 01 08 0e 04 20 00 12 }

	condition:
		uint16( 0 ) == 0x5a4d and filesize < 40KB and 3 of them or 4 of them
}

Strings (10 patterns)

Identifier	Type	Value	Modifiers
$x1	text	"\\Microsoft\\NativeCache\\NativeCacheSvc.dll"	wide
$x2	text	"\\NativeCacheSvc.dll _configNativeCache"	wide
$a1	text	"/content.dropboxapi.com"	wide fullword
$s1	text	"rundll32.exe {0} {1}"	wide fullword
$s2	text	"\\\\CertPKIProvider.dll"	wide
$s3	text	"/tmp/readme.pdf"	wide
$s4	text	"temp/[^\"]*)\""	wide fullword
$op1	hex	{ 00 78 00 2d 00 41 00 50 00 49 00 2d 00 41 00 72 00 67 00 01 2f 4f 00 72 00 }
$op2	hex	{ 25 72 98 01 00 70 6f 34 00 00 0a 25 6f 35 00 00 0a 72 71 02 00 70 72 }
$op3	hex	{ 4d 05 20 00 12 80 91 04 20 01 08 0e 04 20 00 12 }

Condition

uint16( 0 ) == 0x5a4d and filesize < 40KB and 3 of them or 4 of them

In plain words (Heuristic)

The file must start with “MZ” — a Windows executable (PE).
The file must be smaller than 40KB (a cheap guard that skips large files).
At least 3 patterns in the rule must match.
At least 4 patterns in the rule must match.

Test this rule in your browser

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References

https://www.microsoft.com/security/blog/2021/05/28/breaking-down-nobeliums-latest-early-stage-toolset/

Sample hashes

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

0acb884f2f4cfa75b726cb8290b20328c8ddbcd49f95a1d761b7d131b95bafec
8199f309478e8ed3f03f75e7574a3e9bce09b4423bd7eb08bb5bff03af2b7c27
cf1d992f776421f72eabc31d5afc2f2067ae856f1c9c1d6dc643a67cb9349d8c

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: a4144c00-48b2-5520-b773-5d0a5de95fb1

Tags:FILE

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