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VOLEXITY_Malware_Js_Xeskimmer

Detects JScript code using in skimming credit card details.

MalwareVolexity threat-intelBSD 2-Clause LicenseCompiles with YARA-X
Author
threatintel@volexity.com
Date
2021-11-17
Modified
2023-11-14
Score / Quality
75 / 80

What this rule detects

Detects JScript code using in skimming credit card details.

It defines 7 patterns (7 text, 0 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

malware-js-xeskimmer.yarBSD 2-Clause License
rule VOLEXITY_Malware_Js_Xeskimmer : WHEELEDASH FILE
{
	meta:
		description = "Detects JScript code using in skimming credit card details."
		author = "threatintel@volexity.com"
		id = "2c0911cf-a679-5d4e-baad-777745a28e27"
		date = "2021-11-17"
		modified = "2023-11-14"
		reference = "https://github.com/MBThreatIntel/skimmers/blob/master/null_gif_skimmer.js"
		source_url = "https://github.com/volexity/threat-intel/blob/3a9d0b52459877ee866a9a0ba06e60059b778c77/2021/2021-12-06 - XEGroup/indicators/yara.yar#L79-L114"
		license_url = "https://github.com/volexity/threat-intel/blob/3a9d0b52459877ee866a9a0ba06e60059b778c77/LICENSE.txt"
		hash = "92f9593cfa0a28951cae36755d54de63631377f1b954a4cb0474fa0b6193c537"
		logic_hash = "cc46e9fab5f408fde13c3897d378a1a2e4acb448f40ca4935c19024ebdc252d7"
		score = 75
		quality = 80
		tags = "WHEELEDASH, FILE"
		os = "win"
		os_arch = "all"
		scan_context = "file"
		severity = "critical"
		license = "See license at https://github.com/volexity/threat-intel/blob/main/LICENSE.txt"
		rule_id = 6144
		version = 4

	strings:
		$s1 = ".match(/^([3456]\\d{14,15})$/g" ascii
		$s2 = "^(p(wd|ass(code|wd|word)))" ascii
		$b1 = "c('686569676874')" ascii
		$b2 = "c('7769647468')" ascii
		$c1 = "('696D67')" ascii
		$c2 = "('737263')" ascii
		$magic = "d=c.charCodeAt(b),a+=d.toString(16);"

	condition:
		all of ( $s* ) or all of ( $b* ) or all of ( $c* ) or $magic
}

Strings (7 patterns)

IdentifierTypeValueModifiers
$s1text".match(/^([3456]\\d{14,15})$/g"ascii
$s2text"^(p(wd|ass(code|wd|word)))"ascii
$b1text"c('686569676874')"ascii
$b2text"c('7769647468')"ascii
$c1text"('696D67')"ascii
$c2text"('737263')"ascii
$magictext"d=c.charCodeAt(b),a+=d.toString(16);"

Condition

all of ( $s* ) or all of ( $b* ) or all of ( $c* ) or $magic

In plain words (Heuristic)

  • All patterns in ( $s* ) must match.
  • All patterns in ( $b* ) must match.
  • All patterns in ( $c* ) must match.
  • Pattern $magic 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).

  • 92f9593cfa0a28951cae36755d54de63631377f1b954a4cb0474fa0b6193c537

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: 2c0911cf-a679-5d4e-baad-777745a28e27

Metadata

oswin
os_archall
scan_contextfile
severitycritical
rule_id6144
version4

Tags:WHEELEDASHFILE