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YARA · Signature Base (Florian Roth / Nextron)

SIGNATURE_BASE_MAL_Shellcode_Loader_Apr23

Detects Shellcode loader as seen being used by Gopuram backdoor

MalwareGopuramSignature Base (Florian Roth / Nextron)Detection Rule License 1.1Compiles with YARA-X
Author
X__Junior (Nextron Systems)
Date
2023-04-03
Modified
2023-12-05
Score / Quality
80 / 85

What this rule detects

Detects Shellcode loader as seen being used by Gopuram backdoor

Associated malware family: Gopuram.

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

Summary generated from the rule's metadata and condition.

Rule source

Download .yar
mal-shellcode-loader-apr23.yarDetection Rule License 1.1
rule SIGNATURE_BASE_MAL_Shellcode_Loader_Apr23
{
	meta:
		description = "Detects Shellcode loader as seen being used by Gopuram backdoor"
		author = "X__Junior (Nextron Systems)"
		id = "363b67d6-9cac-513d-a545-1f256667bab8"
		date = "2023-04-03"
		modified = "2023-12-05"
		reference = "https://securelist.com/gopuram-backdoor-deployed-through-3cx-supply-chain-attack/109344/"
		source_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/apt_mal_gopuram_apr23.yar#L3-L18"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		hash = "6ce5b6b4cdd6290d396465a1624d489c7afd2259a4d69b73c6b0ba0e5ad4e4ad"
		hash = "b56279136d816a11cf4db9fc1b249da04b3fa3aef4ba709b20cdfbe572394812"
		logic_hash = "e4e423158757c80b5e4e77f6a343323a87798c6697cf6a832aa01a146712b250"
		score = 80
		quality = 85
		tags = ""

	strings:
		$op1 = { 41 C1 CB 0D 0F BE 03 48 FF C3 44 03 D8 80 7B ?? 00 75 ?? 41 8D 04 13 3B C6 74 }
		$op2 = { B9 49 F7 02 78 4C 8B E8 E8 ?? ?? ?? ?? B9 58 A4 53 E5 48 89 44 24 ?? E8 ?? ?? ?? ?? B9 10 E1 8A C3 48 8B F0 E8 ?? ?? ?? ?? B9 AF B1 5C 94 48 89 44 24 ?? E8 }

	condition:
		all of them
}

Strings (2 patterns)

IdentifierTypeValueModifiers
$op1hex{ 41 C1 CB 0D 0F BE 03 48 FF C3 44 03 D8 80 7B ?? 00 75 ?? 41 8D 04 13 3B C6 74 }
$op2hex{ B9 49 F7 02 78 4C 8B E8 E8 ?? ?? ?? ?? B9 58 A4 53 E5 48 89 44 24 ?? E8 ?? ?? ?? ?? B9 10 E1 8A C3 48 8B F0 E8 ?? ?? ?? ?? B9 AF B1 5C 94 48 89 44 24 ?? E8 }

Condition

all of them

In plain words (Heuristic)

  • All patterns in the rule must match.

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References

Sample hashes

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

  • 6ce5b6b4cdd6290d396465a1624d489c7afd2259a4d69b73c6b0ba0e5ad4e4ad
  • b56279136d816a11cf4db9fc1b249da04b3fa3aef4ba709b20cdfbe572394812

Licence & attribution

Author: X__Junior (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: 363b67d6-9cac-513d-a545-1f256667bab8

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