Re: Norton AV 2002 rewriting SMTP, breaking TLS

From: Adam Shostack (adamat_private)
Date: Mon Jul 22 2002 - 07:09:33 PDT

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    On Fri, Jul 19, 2002 at 02:40:16PM -0400, Owen, Greg wrote:
    | > I saw this behavior in Norton AV 2000.  After searching their 
    | > web site, I found the information saying that they just plain
    | > don't support SSL encrypted email.  You have to pick, auto-scan
    | > AV, or encrypted session.
    | 
    | 	I ran into this bug (yes, I'll call it a bug) in Norton a few
    | months ago.  I can only say that there is a special circle in hell
    | reserved for companies which _silently_ disable security measures in
    | order to let their product carry out a procedure (especially a redundant
    | procedure).
    | 
    | 	While we're on STARTTLS issues, another security issue people
    | should be aware of is that mail clients (I've seen this on OE, but I'm
    | betting it is pretty common) only use SSL for encryption, not
    | authentication.  In other words, if you just happen to be in a hotel
    | with one of those ethernet devices, and the hotel ISP happens to
    | silently redirect port 25 to their own SMTP relay, and their SMTP relay
    | supports STARTTLS with a valid certificate, then your mail client will
    | very happily transmit your SMTP AUTH credentials to their server,
    | thinking it is your own that it is talking to.  This one bit me at SANS
    | Orlando 2002 (Thank you, Marriot...)
    
    So if the Marriot can do this, why can't Norton?  
    
    It seems to be the perfect solution; encrypt to the AV product, which
    is doing a MITM attack, and then from the AV product to your mail
    server.
    
    Which of course will make figuring out what the cert on the far end is
    *even trickier*, but hey, its a small price to pay for
    anti-eavesdropping.
    
    Adam
    
    
    
    -- 
    "It is seldom that liberty of any kind is lost all at once."
    					               -Hume
    



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