id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
4531	SessionId collision - session takeover by accident	Frank Tegtmeyer <fte@…>	Adrian Holovaty	"I just had an accidental session takeover at a clients web site.

My session settings:
{{{
SESSION_COOKIE_SECURE = True
SESSION_EXPIRE_AT_BROWSER_CLOSE = True
SESSION_COOKIE_AGE = 70000
}}}


Environment:[[BR]]
Python 2.5, Django SVN Revision: 5320, OpenBSD 4.1, lighttpd with FastCGI

After checking the generation of the sessionid I found that there may be
the following reasons (in combination):

 * very low traffic site (at the moment)
 * I had a very short session before logging in again, I used the logout link (admin interface).
 * no deletion of the session cookie when logging out (not sure about that but it would explain the behaviour)
 * five django processes, each having its own seeded random module
 * exclusive use of fixed data or determined data for the sessionid generation

I think I reused my old sessionid by still having the cookie. Between logging
out and logging in again another user got the same sessionid (because it 
was not in the database anymore). So I got an authenticated session from the
other user.

A patch is provided, maybe even the remote IP should be included in feeding md5.
The session cookie should also be deleted when using a logout link.

Regards, Frank"		closed	Contrib apps	dev		fixed	sessionid session patch		Ready for checkin	1	0	0	1	0	0