phpBB 2.0.23 Session Hijacking Vulnerability

["nbbn@xxxxxxx" <nbbn@xxxxxxx>]

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phpBB 2.0.23 Session Hijacking Vulnerability                +
found by NBBN                 13 Mar 2008                   +
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::Information about this vulnerabilty
If a moderator or an admin close a thread in phpBB 2.0.X, the sessionid 
is sending with GET:

http://site.tld/phpBB2/modcp.php?t=1&mode=lock&sid=[session]

The admin/moderator are going to be redirected to the thread(with the 
session). If an attacker has posted an image in his post, he can see the 
referer and so the session id. And if the attacker have a good day and 
the admin close the thread, he can use all admin-functions with csrf.


::Fix

No fix

::Workaround

Upgrade to phpBB3

::Tested under:

phpBB 2.0.23 (localhost)