mailing list archives
Re: Tying a session to an IP address
From: exon <exon () home se>
Date: Mon, 10 May 2004 16:00:47 +0200
Paul Johnston wrote:
I'd say it doesn't do diddly squat to add to security, since it's
trivial to spoof ones address.
I'm interested in the merits of restricting a session to an IP address.
I realise this isn't great security as often many users will appear to
come from the same IP address (NAT, proxies, etc.) However, if you
consider the case where an attacker uses an XSS vulnerability to steal
the session ID, then the IP address restriction raises the bar
considerably for an arbitrary remote attacker to exploit this. I'm
worried that the IP address restriction wouldn't work for all users -
e.g. if their ISP uses load-balanced web caches. Does anyone know how
common such arrangements are in practice? Perhaps something to be done
then is just check the top 16 bits of the IP address. This is likely to
work for all such network arrangements and still raises the bar a lot
for remote attacks.
Does anyone here already restrict sessions by IP address?