Source:  http://code.google.com/p/skylined/issues/detail?id=23

SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS
                                                                                                                       
   ,dSSSSSSSSSSSS  SSSS    ,dSSY'  SSSS      SSSS  SSSS          SSSS  SSSSb,    SSSS  ,dSSSSSSSSSSSS  SSSSSSSSSSSSb,  
   SSSS            SSSS  ,dSSY'    SSSS      SSSS  SSSS          SSSS  SSSSSSb,  SSSS  SSSS            SSSS      SSSS  
   'YSSSSSSSSSSb,  SSSSSSSSSSSSb,  'YSSSSSSSSSSSS  SSSS          SSSS  SSSS'YSSb,SSSS  SSSSSSSSSSS     SSSS      SSSS  
             SSSS  SSSS      SSSS            SSSS  SSSS          SSSS  SSSS  'YSSSSSS  SSSS            SSSS      SSSS  
   SSSSSSSSSSSSP'  SSSS      SSSS  SSSSSSSSSSSSP'  'YSSSSSSSSSS  SSSS  SSSS    'YSSSS  'YSSSSSSSSSSSS  SSSS  SSSSSSP'  
                                                                                                                       
SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS
                                                                                                                       
 Internet Exploiter 12+DEP: Oracle Java 6 OBJECT tag "launchjnlp"/"docbase" param buffer overflow exploit.             
 Copyright (c) 2010 Berend-Jan "SkyLined" Wever <berendjanwever@gmail.com>                                             
 All rights reserved. This information is provided for academic purpose only.                                          
                                                                                                                       
 This exploit targets a stack based buffer overflow in Oracle Java 6. The vulnerability has been confirmed in Update 20
 and 21 and it probably exists in earlier version as well. The overflow allows control over the EBP and EIP registers  
 when the vulnerable code returns.                                                                                     
                                                                                                                       
 This exploit tries to bypasss DEP using the "Havoc" mechanism first published at                                      
 http://skypher.com/index.php/2010/03/01/internet-exploiter-2-dep/. This is a combination of a heap spray and a        
 ret-into-libc attack that tries to set the executable flag on a block of memory in the heap spray before executing it.
                                                                                                                       
 After setting up the heap spray, the stack overflow in Java is used to overwrite EBP and EIP. EIP is pointed to any   
 LEAVE, RET instruction sequence in the code section of any loaded module at an address that can be encoded in the     
 buffer overflow string (characters [\x00\x80-\x9F] cannot be used!) The LEAVE instruction provides control over ESP,  
 which makes the ret-into-libc attack possible.                                                                        
 The ret-into-libc attack causes consecutive calls to ZwProtectVirtualMemory in ntdll. Each call tries to change the   
 memory protection flags for a memory region that should be covered by the heap spray and contain the shellcode.       
 Multiple calls are needed because the base address of the memory block that contains the shellcode is not know. One   
 call is made for each possible value, and therefore all but one of these calls should fail. After these calls, the    
 ret-into-lic stack returns to the shellcode, which by now should be executable because of the one call to             
 ZwProtectVirtualMemory that succeeded.                                                                                
                                                                                                                       
 This exploit does not attempt to bypass ASLR. When testing on a target with ASLR enabled, you can provide the base    
 address of ntdll by appending "?iNtDllImageBase=0xXXXXXXXX" tot the url. Alternatively, you could try to find a way to
 determine the base address of ntdll automatically or do a brute-force attack that tries all ~256 possible values      
 (hint, hint :D).                                                                                                      
                                                                                                                       
 This exploit has been tested succcessfully on Windows XP sp3 en-us (x86), Windows Vista sp2 en-us (x86) and Windows 7 
 en-us (x64) and with MSIE 6.0, 7.0 and 8.0 using Java 6 Update 21.                                                    
                                                                                                                       
 Redistribution and use in source and binary forms, with or without modification, are permitted provided that the      
 following conditions are met:                                                                                         
    * Redistributions of source code must retain the above copyright notice, this list of conditions and the following 
      disclaimer.                                                                                                      
    * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the        
      following disclaimer in the documentation and/or other materials provided with the distribution.                 
    * Neither the name of the copyright holder nor the names of the contributors may be used to endorse or promote     
      products derived from this software without specific prior written permission.                                   
                                                                                                                       
 THIS SOFTWARE IS PROVIDED ''AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 
 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT    
 HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES   
 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR        
 BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT  
 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE        
 POSSIBILITY OF SUCH DAMAGE.                                                                                           
                                                                                                                       
SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS

Code: http://www.exploit-db.com/sploits/iExploit12-DEP.zip