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YARA · Signature Base (Florian Roth / Nextron)

SIGNATURE_BASE_MAL_Trojan_DLL_Nov23

Detects a trojan DLL that installs other components - was seen being used by LockBit 3.0 affiliates exploiting CVE-2023-4966

MalwareLockbitSignature Base (Florian Roth / Nextron)Detection Rule License 1.1Compiles with YARA-X
Author
X__Junior
Date
2023-11-23
Modified
2023-12-05
Score / Quality
80 / 85

What this rule detects

Detects a trojan DLL that installs other components - was seen being used by LockBit 3.0 affiliates exploiting CVE-2023-4966

Associated malware family: Lockbit.

Targets: Windows PE.

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

Summary generated from the rule's metadata and condition.

Rule source

Download .yar
mal-trojan-dll-nov23.yarDetection Rule License 1.1
rule SIGNATURE_BASE_MAL_Trojan_DLL_Nov23 : CVE_2023_4966 FILE
{
	meta:
		description = "Detects a trojan DLL that installs other components - was seen being used by LockBit 3.0 affiliates exploiting CVE-2023-4966"
		author = "X__Junior"
		id = "1dd87d0a-2b8b-5386-8fdd-40d184c731a4"
		date = "2023-11-23"
		modified = "2023-12-05"
		reference = "https://www.cisa.gov/news-events/cybersecurity-advisories/aa23-325a"
		source_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/apt_ransom_lockbit_citrixbleed_nov23.yar#L24-L39"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		hash = "e557e1440e394537cca71ed3d61372106c3c70eb6ef9f07521768f23a0974068"
		logic_hash = "9be42742711b4d0440244b507945e074b61c456588580b3263f899a7eb84d8aa"
		score = 80
		quality = 85
		tags = "CVE-2023-4966, FILE"

	strings:
		$op1 = { C7 84 24 ?? ?? ?? ?? 52 70 63 53 C7 84 24 ?? ?? ?? ?? 74 72 69 6E C7 84 24 ?? ?? ?? ?? 67 42 69 6E C7 84 24 ?? ?? ?? ?? 64 69 6E 67 C7 84 24 ?? ?? ?? ?? 43 6F 6D 70 C7 84 24 ?? ?? ?? ?? 6F 73 65 41 C7 84 24 ?? ?? ?? ?? 00 40 01 01 }
		$op2 = { C7 84 24 ?? ?? ?? ?? 6C 73 61 73 C7 84 24 ?? ?? ?? ?? 73 70 69 72 66 C7 84 24 ?? ?? 00 00 70 63 }
		$op3 = { C7 84 24 ?? ?? ?? ?? 4E 64 72 43 C7 84 24 ?? ?? ?? ?? 6C 69 65 6E C7 84 24 ?? ?? ?? ?? 74 43 61 6C C7 84 24 ?? ?? ?? ?? 6C 33 00 8D }

	condition:
		uint16( 0 ) == 0x5a4d and all of them
}

Strings (3 patterns)

IdentifierTypeValueModifiers
$op1hex{ C7 84 24 ?? ?? ?? ?? 52 70 63 53 C7 84 24 ?? ?? ?? ?? 74 72 69 6E C7 84 24 ?? ?? ?? ?? 67 42 69 6E C7 84 24 ?? ?? ?? ?? 64 69 6E 67 C7 84 24 ?? ?? ?? ?? 43 6F …
$op2hex{ C7 84 24 ?? ?? ?? ?? 6C 73 61 73 C7 84 24 ?? ?? ?? ?? 73 70 69 72 66 C7 84 24 ?? ?? 00 00 70 63 }
$op3hex{ C7 84 24 ?? ?? ?? ?? 4E 64 72 43 C7 84 24 ?? ?? ?? ?? 6C 69 65 6E C7 84 24 ?? ?? ?? ?? 74 43 61 6C C7 84 24 ?? ?? ?? ?? 6C 33 00 8D }

Condition

uint16( 0 ) == 0x5a4d and all of them

In plain words (Heuristic)

  • The file must start with “MZ” — a Windows executable (PE).
  • 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).

  • e557e1440e394537cca71ed3d61372106c3c70eb6ef9f07521768f23a0974068

Licence & attribution

Author: X__Junior

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: 1dd87d0a-2b8b-5386-8fdd-40d184c731a4

Tags:CVE_2023_4966FILE

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