Skip to content
yararules.org
Menu

YARA · Signature Base (Florian Roth / Nextron)

SIGNATURE_BASE_MAL_Python_Backdoor_Script_Nov23

Detects a trojan (written in Python) that communicates with c2 - 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 (written in Python) that communicates with c2 - was seen being used by LockBit 3.0 affiliates exploiting CVE-2023-4966

Associated malware family: Lockbit.

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

Summary generated from the rule's metadata and condition.

Rule source

Download .yar
mal-python-backdoor-script-nov23.yarDetection Rule License 1.1
rule SIGNATURE_BASE_MAL_Python_Backdoor_Script_Nov23 : CVE_2023_4966 FILE
{
	meta:
		description = "Detects a trojan (written in Python) that communicates with c2 - was seen being used by LockBit 3.0 affiliates exploiting CVE-2023-4966"
		author = "X__Junior"
		id = "861f9ce3-3c54-5c56-b50b-2b7536783f6e"
		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#L56-L71"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		hash = "906602ea3c887af67bcb4531bbbb459d7c24a2efcb866bcb1e3b028a51f12ae6"
		logic_hash = "b336f6438a420af49b1b0144039f1051f12c0c54f77a94e2f947f71d1f6230b3"
		score = 80
		quality = 85
		tags = "CVE-2023-4966, FILE"

	strings:
		$s1 = "port = 443 if \"https\"" ascii
		$s2 = "winrm.Session basic error" ascii
		$s3 = "Windwoscmd.run_cmd(str(cmd))" ascii

	condition:
		filesize < 50KB and all of them
}

Strings (3 patterns)

IdentifierTypeValueModifiers
$s1text"port = 443 if \"https\""ascii
$s2text"winrm.Session basic error"ascii
$s3text"Windwoscmd.run_cmd(str(cmd))"ascii

Condition

filesize < 50KB and all of them

In plain words (Heuristic)

  • The file must be smaller than 50KB (a cheap guard that skips large files).
  • All patterns in the rule must match.

Test this rule in your browser

Drop a file to scan it with this rule using YARA-X compiled to WebAssembly. Nothing is uploaded.

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

Open in editor

References

Sample hashes

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

  • 906602ea3c887af67bcb4531bbbb459d7c24a2efcb866bcb1e3b028a51f12ae6

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: 861f9ce3-3c54-5c56-b50b-2b7536783f6e

Tags:CVE_2023_4966FILE

Related rules

More Lockbit rules