Re: Solution for session_regenerate_id() issues

On Thu, Mar 13, 2014 at 01:03:15PM +0900, Yasuo Ohgaki wrote: > Hi all, > > Current session_regenerate_id() has issues. I'll try to explain what these > are. > > Issue 1: Old session data is not deleted. > > session_regenerate_id() does not delete old session by default. It leaves > old session available. When attacker could steal session ID via > XSS/sniffing/etc, attacker can use session ID as valid ID as long as > application allows. No detection/prevention of security breach is possible > at session module level. This behavior is unacceptable for security reason. > > Issue 2: Old session data cannot be deleted. > > session_regenerate_id(TRUE) deletes old session data immediately. It's good > for security, but if there are multiple connections from a client to server > (e.g. AJAX/iframe/tabs/etc), valid connection may fail since it could be > using old session ID. Therefore, session_regenerate_id() does not delete > old session data. Immediate session data deletion is unacceptable for > reliable operation. > > To solve these 2 issues, we need to delay old session data deletion. Delete > old session data 60 seconds later, for example. > > If there is any other feasible solutions are welcome. I cannot think of any. > > Regards, > > P.S. Even with HTTP 2.0, old session data cannot be deleted immediately. > User may use multiple tabs. I'm not sure if we should handle that in PHP, application usually regenerates session on important events (i.e. on user login/logout etc.), so any requests with old session should be denied, and this can be achieved using session_regenerate_id(TRUE). Wouldn't it be better to write a security note in the documentation rather than making whole thing more complex? Regards, Mateusz