Subject: [lemonade] Updated RECONNECT draft

From: Alexey Melnikov <[email-masked]>
Date: Mon, 07 Mar 2005 17:07:36 +0000

Sorry, I've missed the deadline. The latest version is available at:
<http://ietf.webdav.org/users/amelnikov/draft-ietf-lemonade-reconnect-03.txt>

Alexey

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From: Rob Siemborski <[email-masked]>
Date: Mon, 7 Mar 2005 17:30:35 -0500 (EST)

> <http://ietf.webdav.org/users/amelnikov/draft-ietf-lemonade-reconnect-03.txt>

I think there might be an active attack against this extension (at least 
when integrity protection is negotiated by the AUTHENTICATE command).

In this case, the SID has been passed from the client to server, but may 
have been modified in transit.  When the server authenticates the client, 
it doesn't verify that the correct SID was actually received once the 
integrity layer is active.

I think this can be fixed by having the server *always* send the SID back 
to the client after the authentication succeeds, as opposed to only when 
the SID is changing (note that we shouldn't use the NEWSID response for 
this).  If the SIDs don't match, the client knows that an attack is in 
progress.

I'm not really sure what the purpose of this attack would be, but there it 
is.

-Rob

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Rob Siemborski        |     PGP:0x5CE32FCC     |      [email-masked] 
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