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YARA · BlackBerry Research & Intelligence (via Open-Source-YARA-rules)

BLACKBERRY_Mal_Win32_Onyx_Strain_Chaos_Ransomware_2022

Detects Onyx Ransomware build off of Chaos Builder v4

MalwareBlackBerry Research & Intelligence (via Open-Source-YARA-rules)Apache License 2.0Compiles with YARA-X
Author
BlackBerry Threat Research
Date
2022-05-10
Modified
2022-07-07
Score / Quality
75 / 85

What this rule detects

Detects Onyx Ransomware build off of Chaos Builder v4

Targets: Windows PE.

It defines 3 patterns (3 text, 0 hex, 0 regex). YARA modules used: pe.

Summary generated from the rule's metadata and condition.

Rule source

Includes the imports needed to compile it on its own.

mal-win32-onyx-strain-chaos-ransomware-2022.yarApache License 2.0
import "pe"

rule BLACKBERRY_Mal_Win32_Onyx_Strain_Chaos_Ransomware_2022 : FILE
{
	meta:
		description = "Detects Onyx Ransomware build off of Chaos Builder v4"
		author = "BlackBerry Threat Research"
		id = "8c30c316-9fd3-5ad9-aea1-d93229cd9ca1"
		date = "2022-05-10"
		modified = "2022-07-07"
		reference = "https://blogs.blackberry.com/en/2022/05/yashma-ransomware-tracing-the-chaos-family-tree"
		source_url = "https://github.com/mikesxrs/Open-Source-YARA-rules/blob/ec0056f767db98bf6d5fd63877ad51fb54d350e9/Blackberry/Mal_Win32_Onyx_Strain_Chaos_Ransomware_2022.yar#L3-L28"
		license_url = "N/A"
		logic_hash = "2df2f36167710a4de4ff3fda8036472b1972b4175a0d14f8b06e0ad045eb5038"
		score = 75
		quality = 85
		tags = "FILE"
		license = "This Yara rule is provided under the Apache License 2.0 (https://www.apache.org/licenses/LICENSE-2.0) and open to any user or organization, as long as you use it under this license and ensure originator credit in any derivative to The BlackBerry Research & Intelligence Team"

	strings:
		$s1 = "(?:[13]{1}[a-km-zA-HJ-NP-Z1-9]{26,33}|bc1[a-z0-9]{39,59})" wide
		$s2 = "All of your files are currently encrypted by ONYX strain." wide
		$s3 = "Inform your supervisors and stay calm!" wide

	condition:
		uint16( 0 ) == 0x5a4d and pe.data_directories [ pe.IMAGE_DIRECTORY_ENTRY_COM_DESCRIPTOR ] . size != 0 and all of ( $s* )
}

Strings (3 patterns)

IdentifierTypeValueModifiers
$s1text"(?:[13]{1}[a-km-zA-HJ-NP-Z1-9]{26,33}|bc1[a-z0-9]{39,59})"wide
$s2text"All of your files are currently encrypted by ONYX strain."wide
$s3text"Inform your supervisors and stay calm!"wide

Condition

uint16( 0 ) == 0x5a4d and pe.data_directories [ pe.IMAGE_DIRECTORY_ENTRY_COM_DESCRIPTOR ] . size != 0 and all of ( $s* )

In plain words (Heuristic)

  • The file must start with “MZ” — a Windows executable (PE).
  • All patterns in ( $s* ) must match.
  • Uses the pe module.

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References

Licence & attribution

Author: BlackBerry Threat Research

Source repository: BlackBerry Research & Intelligence (via Open-Source-YARA-rules) @ ec0056f767

Licence: Apache License 2.0 (stated in the rule's own meta)

“This Yara rule is provided under the Apache License 2.0 (https://www.apache.org/licenses/LICENSE-2.0) and open to any user or organization, as long as you use it under this license and ensure originator credit in any derivative to The BlackBerry Research & Intelligence Team”

Original rule

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

Rule id: 8c30c316-9fd3-5ad9-aea1-d93229cd9ca1

Tags:FILE