Boston Linux & UNIX was originally founded in 1994 as part of The Boston Computer Society. We meet on the third Wednesday of each month at the Massachusetts Institute of Technology, in Building E51.

BLU Discuss list archive

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[Discuss] comcast wifi question

> From: Tom Metro [mailto:tmetro+blu at]
>   WPA-PSK and WPA2-PSK encrypt everything with per-client, per-session
>   keys, but those keys are derived from the Pre-Shared Key (the PSK; the
>   key you have to know to get on the network) plus some information
>   exchanged in the clear when the client joins or re-joins the network.
>   So if you know the PSK for the network, and your sniffer catches the
>   "4-way handshake" another client does with the AP as it joins, you can
>   decrypt all of that client's traffic. If you didn't happen to capture
>   that client's 4-way handshake, you can send a spoofed de-authenticate
>   packet to the target client (spoofing it to make it look like it came
>   from the AP's MAC address), forcing the client to fall off the network
>   and get back on, so you can capture its 4-way handshake this time, and
>   decrypt all further traffic to/from that client.

Additionally, if you get on the network and want to attack another client on the same wifi connection, there's an awful lot of broadcast traffic exposure which is not protected by the session keys, and you can target packets to their specific IP address, will also not be protected by their session keys.  The only thing that's protected by their session keys are their non-broadcast traffic to *other* endpoints.

Based on what you wrote above, even that seems pretty easy to break.

BLU is a member of BostonUserGroups
BLU is a member of BostonUserGroups
We also thank MIT for the use of their facilities.

Valid HTML 4.01! Valid CSS!

Boston Linux & Unix /