YARA · Signature Base (Florian Roth / Nextron)

SIGNATURE_BASE_APT_MAL_LNX_Kobalos

Kobalos malware

APT / threat actorSignature Base (Florian Roth / Nextron)BSD 2-Clause LicenseCompiles with YARA-X

Author: Marc-Etienne M.Leveille
Date: 2020-11-02
Modified: 2023-12-05
Score / Quality: 75 / 85

What this rule detects

Kobalos malware

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

Summary generated from the rule's metadata and condition.

Rule source

Download .yar

apt-mal-lnx-kobalos.yarBSD 2-Clause License

rule SIGNATURE_BASE_APT_MAL_LNX_Kobalos : FILE
{
	meta:
		description = "Kobalos malware"
		author = "Marc-Etienne M.Leveille"
		id = "dfa47e30-c093-57f6-af01-72a2534cc6f4"
		date = "2020-11-02"
		modified = "2023-12-05"
		reference = "https://github.com/eset/malware-ioc/"
		source_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/apt_lnx_kobalos.yar#L32-L57"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		logic_hash = "48aec47b70633d4c8cb55d90a2e168f3c2027ef27cfe1cd5d30dcdc08a2ff717"
		score = 75
		quality = 85
		tags = "FILE"
		license = "BSD 2-Clause"
		version = "1"

	strings:
		$encrypted_strings_sizes = {
            05 00 00 00 09 00 00 00  04 00 00 00 06 00 00 00
            08 00 00 00 08 00 00 00  02 00 00 00 02 00 00 00
            01 00 00 00 01 00 00 00  05 00 00 00 07 00 00 00
            05 00 00 00 05 00 00 00  05 00 00 00 0A 00 00 00
        }
		$password_md5_digest = { 3ADD48192654BD558A4A4CED9C255C4C }
		$rsa_512_mod_header = { 10 11 02 00 09 02 00 }
		$strings_rc4_key = { AE0E05090F3AC2B50B1BC6E91D2FE3CE }

	condition:
		uint16( 0 ) == 0x457f and any of them
}

Strings (4 patterns)

Identifier	Type	Value
$encrypted_strings_sizes	hex	{ 05 00 00 00 09 00 00 00 04 00 00 00 06 00 00 00 08 00 00 00 08 00 00 00 02 00 00 00 02 00 00 00 01 00 00 00 01 00 00 00 …
$password_md5_digest	hex	{ 3ADD48192654BD558A4A4CED9C255C4C }
$rsa_512_mod_header	hex	{ 10 11 02 00 09 02 00 }
$strings_rc4_key	hex	{ AE0E05090F3AC2B50B1BC6E91D2FE3CE }

Condition

uint16( 0 ) == 0x457f and any of them

In plain words (Heuristic)

At least one pattern in the rule must match.

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References

https://github.com/eset/malware-ioc/

Licence & attribution

Author: Marc-Etienne M.Leveille

Source repository: Signature Base (Florian Roth / Nextron) @ 94a1c48d7a

Licence: BSD 2-Clause License (stated in the rule's own meta)

“BSD 2-Clause”

Original rule

Mirrored via YARA Forge 20260927, which prefixes rule names with the source and adds normalised meta fields.

Rule id: dfa47e30-c093-57f6-af01-72a2534cc6f4

Metadata

version	1

Tags:FILE

SIGNATURE_BASE_APT_MAL_LNX_Kobalos_SSH_Credential_Stealer
APT / threat actorSignature Base (Florian Roth / Nextron)· Marc-Etienne M.Leveille· 2020-11-02