YARA · Volexity threat-intel

VOLEXITY_Informational_Win_3Cx_Msi

Detects 3CX installers created in March 2023, 3CX was known to be compromised at this time.

GenericVolexity threat-intelBSD 2-Clause LicenseCompiles with YARA-X

Author: threatintel@volexity.com
Date: 2023-03-30
Score / Quality: 75 / 80

What this rule detects

Detects 3CX installers created in March 2023, 3CX was known to be compromised at this time.

It defines 3 patterns (2 text, 1 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

Download .yar

informational-win-3cx-msi.yarBSD 2-Clause License

rule VOLEXITY_Informational_Win_3Cx_Msi : UTA0040
{
	meta:
		description = "Detects 3CX installers created in March 2023, 3CX was known to be compromised at this time."
		author = "threatintel@volexity.com"
		id = "ac26e7b1-61eb-5074-bcda-46d714bdba4c"
		date = "2023-03-30"
		modified = "2023-03-30"
		reference = "https://www.reddit.com/r/crowdstrike/comments/125r3uu/20230329_situational_awareness_crowdstrike/"
		source_url = "https://github.com/volexity/threat-intel/blob/3a9d0b52459877ee866a9a0ba06e60059b778c77/2023/2023-03-30 3CX/indicators/rules.yar#L134-L152"
		license_url = "https://github.com/volexity/threat-intel/blob/3a9d0b52459877ee866a9a0ba06e60059b778c77/LICENSE.txt"
		hash = "aa124a4b4df12b34e74ee7f6c683b2ebec4ce9a8edcf9be345823b4fdcf5d868"
		logic_hash = "c04de2653ef587f27c7ebf058c6f6c345e16b67f36ccc4306bc49f8c4394728e"
		score = 75
		quality = 80
		tags = "UTA0040"
		memory_suitable = 0
		license = "See license at https://github.com/volexity/threat-intel/blob/main/LICENSE.txt"

	strings:
		$cert = { 1B 66 11 DF 9C 9A 4D 6E CC 8E D5 0C 9B 91 78 73 }
		$app = "3CXDesktopApp.exe"
		$data = "202303"

	condition:
		all of them
}

Strings (3 patterns)

Identifier	Type	Value
$cert	hex	{ 1B 66 11 DF 9C 9A 4D 6E CC 8E D5 0C 9B 91 78 73 }
$app	text	"3CXDesktopApp.exe"
$data	text	"202303"

Condition

all of them

In plain words (Heuristic)

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

https://www.reddit.com/r/crowdstrike/comments/125r3uu/20230329_situational_awareness_crowdstrike/

Sample hashes

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

aa124a4b4df12b34e74ee7f6c683b2ebec4ce9a8edcf9be345823b4fdcf5d868

Licence & attribution

Author: threatintel@volexity.com

Source repository: Volexity threat-intel @ 3a9d0b5245

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

“See license at https://github.com/volexity/threat-intel/blob/main/LICENSE.txt”

Original rule

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

Rule id: ac26e7b1-61eb-5074-bcda-46d714bdba4c

Metadata

memory_suitable	0

Tags:UTA0040

VOLEXITY_Apt_Win_Iconicstealer
APT / threat actorVolexity threat-intel· threatintel@volexity.com· 2023-03-30
VOLEXITY_Apt_Mac_Iconic
APT / threat actorVolexity threat-intel· threatintel@volexity.com· 2023-03-30
VOLEXITY_Apt_Win_3Cx_Backdoored_Lib
APT / threat actorVolexity threat-intel· threatintel@volexity.com· 2023-03-30
VOLEXITY_Apt_Ico_Uta0040_B64_C2
APT / threat actorVolexity threat-intel· threatintel@volexity.com· 2023-03-30
VOLEXITY_Apt_Malware_Win_Deepdata_Module
APT / threat actorVolexity threat-intel· threatintel@volexity.com· 2024-07-30
VOLEXITY_Apt_Malware_Py_Dustpan_Pyloader
APT / threat actorVolexity threat-intel· threatintel@volexity.com· 2023-07-21
VOLEXITY_Apt_Malware_Win_Dustpan_Apihashes
APT / threat actorVolexity threat-intel· threatintel@volexity.com· 2023-08-17
VOLEXITY_Apt_Delivery_Macro_Lazypine_Jeus_B
APT / threat actorVolexity threat-intel· threatintel@volexity.com· 2022-11-03