Xoops 2.5.7.2 Directory Traversal Bypass

[+] Credits: John Page aka hyp3rlinx

[+] Website: hyp3rlinx.altervista.org

[+] Source:  http://hyp3rlinx.altervista.org/advisories/XOOPS-DIRECTORY-TRAVERSAL.txt



Vendor:
=============
xoops.org



Product:
================
Xoops 2.5.7.2



Vulnerability Type:
===========================
Directory Traversal Bypass



Vulnerability Details:
=====================

Xoops 2.5.7.2 has checks to defend against directory traversal attacks. However, they can be easily bypassed by simply issuing "..././" instead of "../"


References:
http://xoops.org/modules/news/article.php?storyid=6757


Exploit Codes:
==============


In Xoops code in 'protector.php' the following check is made for dot dot slash "../" in HTTP requests

////////////////////////////////////////////////////////////
/////////////////////

if( is_array( $_GET[ $key ] ) ) continue ;
if ( substr( trim( $val ) , 0 , 3 ) == '../' || strstr( $val , '../../' ) ) {
 $this->last_error_type = 'DirTraversal' ;
 $this->message .= "Directory Traversal '$val' found.\n" ;

////////////////////////////////////////////////////////////////////////////////

The above Xoops directory traversal check can be defeated by using  ..././..././..././..././

you can test the theory by using example below test case by supplying ..././ to GET param.

$val=$_GET['c'];

if ( substr( trim( $val ) , 0 , 3 ) == '../' || strstr( $val , '../../' ) ) {
echo "traversal!";
}else{
echo "ok!" . $val;
}



Disclosure Date:
==================================
Feb 2, 2016: Vendor Notification
Vendor confirms and patches Xoops
March 17, 2016 : Public Disclosure

==================================

[+] Disclaimer
Permission is hereby granted for the redistribution of this advisory, provided that it is not altered except by reformatting it, and that due credit is given. Permission is explicitly given for insertion in vulnerability databases and similar, provided that due credit is given to the author.
The author is not responsible for any misuse of the information contained herein and prohibits any malicious use of all security related information or exploits by the author or elsewhere. (c) hyp3rlinx.

hyp3rlinx