User: Password:
Subscribe / Log in / New account

A not-security-geek question

A not-security-geek question

Posted Nov 5, 2010 15:08 UTC (Fri) by rmano (guest, #49886)
Parent article: Gathering session cookies with Firesheep

I know that maybe this is not the best place to ask, but, as lwn people is so nice, I will...

Is this problem present when you connect to a wifi network that "seems" to be open, redirect you to a vendor page, and you make a login now to enter (I mean, hotels, airports, wifi spots, etc.)? I do not know how you auth is granted after login, but I suspect is a simple MAC register - so should we consider that kind of networks dangerous as well?


(Log in to post comments)

A not-security-geek question

Posted Nov 5, 2010 22:33 UTC (Fri) by Kwi (subscriber, #59584) [Link]

Yes, as long as the wifi network is unencrypted, it's vulnerable to this attack. The attacker wouldn't even need a login.

Encryption is the only viable defense, whether it's an encrypted wifi (but note that the encryption ends at the access point, leaving you vulnerable to the network owner, and possibly other users, depending on setup), encryption at the application layer (e.g. https), or an encrypted tunnel (e.g. SSH or a full VPN).

A not-security-geek question

Posted Nov 9, 2010 0:23 UTC (Tue) by adisaacs (guest, #53996) [Link]

Partly right, partly wrong.

Yes, an unencrypted 802.11 network is trivially sniffable, whether or not it uses "captive portal" logins.

However, an encrypted wifi is not very much better. WEP is completely broken against eavesdropping even without the attacker knowing the passphrase. WPA is effective against eavesdroppers, but (AFAIK) anyone who knows the PSK can still decrypt captured WPA traffic.

There are more sophisticated variants of WPA (labelled "Enterprise" in the jargon of the trade), but they're significantly more difficult to set up and a total non-starter for the coffeeshop/hotel use case. (They generally require a SecurID-style token of some kind.)

And finally, yes -- a VPN, encrypted tunnel, or application-layer encryption system such as HTTPS is more secure.

Copyright © 2017, Eklektix, Inc.
Comments and public postings are copyrighted by their creators.
Linux is a registered trademark of Linus Torvalds