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VOLEXITY_Apt_Delivery_Web_Js_Jmask_Str_Array_Variant

Detects the JMASK profiling script in an obfuscated format using a string array and an offset.

APT / threat actorVolexity threat-intelBSD 2-Clause LicenseCompiles with YARA-X (with warnings)
Author
threatintel@volexity.com
Date
2023-06-27
Modified
2023-09-21
Score / Quality
75 / 80

What this rule detects

Detects the JMASK profiling script in an obfuscated format using a string array and an offset.

It defines 17 patterns (17 text, 0 hex, 0 regex).

YARA-X says: warning[duplicate_pattern_value]: duplicate pattern value

Summary generated from the rule's metadata and condition.

Rule source

apt-delivery-web-js-jmask-str-array-variant.yarBSD 2-Clause License
rule VOLEXITY_Apt_Delivery_Web_Js_Jmask_Str_Array_Variant : EVILBAMBOO FILE
{
	meta:
		description = "Detects the JMASK profiling script in an obfuscated format using a string array and an offset."
		author = "threatintel@volexity.com"
		id = "d5d32c8b-53fb-5103-ac73-05f320e71c97"
		date = "2023-06-27"
		modified = "2023-09-21"
		reference = "https://github.com/volexity/threat-intel"
		source_url = "https://github.com/volexity/threat-intel/blob/3a9d0b52459877ee866a9a0ba06e60059b778c77/2023/2023-09-22 EvilBamboo/indicators/rules.yar#L408-L444"
		license_url = "https://github.com/volexity/threat-intel/blob/3a9d0b52459877ee866a9a0ba06e60059b778c77/LICENSE.txt"
		hash = "7995c382263f8dbbfc37a9d62392aef8b4f89357d436b3dd94dea842f9574ecf"
		logic_hash = "0ae7c96e0f866f21d66d7a23bf937d6ce48c9dd1ea19142dbb13487208780146"
		score = 75
		quality = 80
		tags = "EVILBAMBOO, FILE"
		scan_context = "file"
		license = "See license at https://github.com/volexity/threat-intel/blob/main/LICENSE.txt"

	strings:
		$array_1 = "http://eular.github.io"
		$array_2 = "stun:stun.services.mozilla.com"
		$array_3 = "\xE6\x9C\xAA\xE5\xAE\x89\xE8\xA3\x85MetaMask"
		$array_4 = "/jquery/jquery.min.js"
		$array_5 = "onicecandidate"
		$ios_1 = "['a7', '640x1136', [_0x"
		$ios_2 = "['a7', _0x"
		$ios_3 = "['a8', _0x"
		$ios_4 = "['a8', '750x1334', ['iPhone\\x206']]"
		$ios_5 = "['a8', '1242x2208', ['iPhone\\x206\\x20Plus']]"
		$ios_6 = "['a8', _0x"
		$ios_7 = "['a9', _0x"
		$ios_8 = "['a9', '750x1334', [_0x"
		$ios_9 = "['a9', '1242x2208', ['iPhone\\x206s\\x20Plus']]"
		$ios_10 = "['a9x', '2048x2732', ['iPad\\x20Pro\\x20(1st\\x20gen\\x2012.9-inch)']]"
		$ios_11 = "['a10x', '1668x2224', [_0x"
		$header = "info = {}, finished = 0x0;"

	condition:
		3 of ( $array_* ) or 5 of ( $ios_* ) or $header
}

Strings (17 patterns)

IdentifierTypeValueModifiers
$array_1text"http://eular.github.io"
$array_2text"stun:stun.services.mozilla.com"
$array_3text"\xE6\x9C\xAA\xE5\xAE\x89\xE8\xA3\x85MetaMask"
$array_4text"/jquery/jquery.min.js"
$array_5text"onicecandidate"
$ios_1text"['a7', '640x1136', [_0x"
$ios_2text"['a7', _0x"
$ios_3text"['a8', _0x"
$ios_4text"['a8', '750x1334', ['iPhone\\x206']]"
$ios_5text"['a8', '1242x2208', ['iPhone\\x206\\x20Plus']]"
$ios_6text"['a8', _0x"
$ios_7text"['a9', _0x"
$ios_8text"['a9', '750x1334', [_0x"
$ios_9text"['a9', '1242x2208', ['iPhone\\x206s\\x20Plus']]"
$ios_10text"['a9x', '2048x2732', ['iPad\\x20Pro\\x20(1st\\x20gen\\x2012.9-inch)']]"
$ios_11text"['a10x', '1668x2224', [_0x"
$headertext"info = {}, finished = 0x0;"

Condition

3 of ( $array_* ) or 5 of ( $ios_* ) or $header

In plain words (Heuristic)

  • At least 3 patterns in ( $array_* ) must match.
  • At least 5 patterns in ( $ios_* ) must match.
  • Pattern $header must be present.

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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).

  • 7995c382263f8dbbfc37a9d62392aef8b4f89357d436b3dd94dea842f9574ecf

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”

Copyright notice: Copyright 2022 by Volexity, Inc.

Original rule

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

Rule id: d5d32c8b-53fb-5103-ac73-05f320e71c97

Metadata

scan_contextfile

Tags:EVILBAMBOOFILE