[MajorSecurity Advisory #51]Virtual Hosting Control System - Session fixation Issue

Details
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Product: Virtual Hosting Control System
Affected version: 2.4.7.1 and prior
Remote-Exploit: yes
Vendor-URL: http://www.vhcs.net
Vendor-Status: informed
Advisory-Status: published

Credits
============
Discovered by: David Vieira-Kurz
http://www.majorsecurity.de

Original Advisory:
============
http://www.majorsecurity.de/index_2.php?major_rls=major_rls51

Introduction
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"VHCS is a Professional Control Panel Software for shared, reseller, virtual and dedicated server management." - from vhcs.net

More Details
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1. Session fixation:
The "PHPSESSID" parameter can be set to a malicious and arbitrary value.

1.1 Description:
In a session fixation attack, the attacker fixes the user's session ID before the user even logs into the target server.
After a user's session ID has been fixed, the attacker will wait for them to login.
Once the user does so, the attacker uses the predefined session ID value to assume their online identity.

PoC:
============
http://localhost/vhcs2-2.4.7.1/gui/?PHPSESSID=15031988

Workaround:
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1. Do not accept session identifiers from GET / POST variables.

2.Regenerate SID on each request.

3. Accept only server generated SID:
One way to improve security is to not accept session identifiers not generated by server.

if ( ! isset( $_SESSION['SERVER_GENERATED_SID'] ) ) {
session_destroy(); // destroy all data in session
}
session_regenerate_id(); // generate a new session identifier
$_SESSION['SERVER_GENERATED_SID'] = true;


History/Timeline
================
18.07.2007 discovery of the vulnerability
20.07.2007 contacted the vendor
20.07.2007 hotfix sent to the vendor 
21.07.2007 advisory is written
21.07.2007 advisory released


MajorSecurity
=======
MajorSecurity is a non-profit German penetration testing and security research project
which consists of only one person at the present time.
http://www.majorsecurity.de/