On Wed, Oct 18, 2017 at 02:29:56PM -0400, Keith Wright wrote:
> This is very embarrassing for the authors of the
> standard, but is it really a big problem? Several
> meetings ago, somebody brought a device to the
> WLUG meeting that, as I understood it, pretends
> to be a wireless router and interposes itself
> into any nearby connection. If things like that
> exist, why care about encryption vulnerability?
Because with properly configured wireless and patched clients, you can
be sure you are connecting to the trusted network, not a
Man-in-the-Middle. It requires mutual authentication, which happens
for example on the WPI wireless network by using EAP-TLS certificates.
The client is supposed to verify the server's certificate and the
server of course verifies the client's certificate. Unfortunately,
most networks don't use EAP but rather use Pre-Shared Keys (WPA2-PSK).
> If you need to patch both sides to be secure,
> then you are not secure in the coffee shop no
> matter what you do. In any case, if you are
> using the wireless to connect to a web site
> or "cloud" server, then the wireless connection
> is the least of your insecurities.
In the strictest sense this is true, but as far as the KRACK attack
goes, the wireless AP side is much less likely to be a problem,
because the vulnerabilities are in parts of the standards that are not
often used (802.11r "Fast Roaming" for example). The client-side
vulnerabilities, especially in Linux/Android, are much more serious.
On Linux, the client can be tricked into using a null session key.
However, in a coffee shop KRACK is moot because most coffee shops
don't use encryption at all to begin with.
In any case, WPI's recommendation to use the VPN if you are not sure
of your device's or the network's immunity to KRACK is sound, because
even if there was a M-i-t-M, they still would not be able to decrypt
the VPN traffic. Security is helpful in layers. Belt-and-suspenders.
