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Re: [TLS] Rizzo claims implementation attach, should be interesting

Yoav Nir <ynir@checkpoint.com> Thu, 29 September 2011 18:07 UTC

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From: Yoav Nir <ynir@checkpoint.com>
To: "mrex@sap.com" <mrex@sap.com>
Date: Thu, 29 Sep 2011 21:09:45 +0300
Thread-Topic: [TLS] Rizzo claims implementation attach, should be interesting
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Cc: "asteingruebl@paypal-inc.com" <asteingruebl@paypal-inc.com>, "tls@ietf.org" <tls@ietf.org>
Subject: Re: [TLS] Rizzo claims implementation attach, should be interesting
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On Sep 29, 2011, at 4:44 PM, Martin Rex wrote:

>> I believe there was a mitigation put in place by OpenSSL: sending an 
>> empty (just padding) message before each app data message. The document 
>> at eprint.iacr.org/2006/136 suggests that this could be a server-side 
>> only change. I don't see how that would work since the session cookie 
>> recovery attack is clearly happening on the client->server channel.
>> 
>> I read somewhere that this mitigation was off by default in OpenSSL 
>> because it some software (an old MSIE IIRC).
> 
> Why using a EMPTY (just padding) SSL record?  That looks like an
> obvious untested border case.
> 
> How about using an initial SSL record with one byte of real data
> for SSLv3 and TLSv1.0 SSL with CBC cipher suites?

Interesting idea.
http://src.chromium.org/viewvc/chrome?view=rev&revision=97269

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