Re: [TLS] Deprecating alert levels

Hi list,

I recently saw a related CVE regarding OpenSSL on oss-security mailing
list: CVE-2016-8610. The original mail is
http://seclists.org/oss-sec/2016/q4/224. As I understand it, the idea is
to send a continuous flow of unauthenticated, warning-level alerts in
the middle of the initial handshake. This leads OpenSSL to keep the
connection open (and apparently to consume some CPU).

Even if this might not be the attack of the century, it may also be
another reason to reconsider how a TLS stack should handle
[multiple|warning|unauthenticated] alerts.

olivier

Le 25/10/2016 03:14, Kyle Nekritz a écrit :
> +1 to both Martin and ekr, I think simplifying these alerts with clearly defined behavior for each alert description is the best way forward.
>
> Kyle 
>
> -----Original Message-----
> From: TLS [mailto:tls-bounces@ietf.org] On Behalf Of Martin Thomson
> Sent: Wednesday, October 19, 2016 10:18 PM
> To: Eric Rescorla <ekr@rtfm.com>
> Cc: tls@ietf.org
> Subject: Re: [TLS] Deprecating alert levels
>
> On 20 October 2016 at 05:28, Eric Rescorla <ekr@rtfm.com> wrote:
>>> 2.  Are there cases, such as unrecognized name. where it is useful to 
>>> indicate that an alert is not fatal?  If so how should this case be handled?
>>
>> I think this alert was a mistake :)
> In NSS is to tolerate it, but it's an exception.  I'm happier with a lone exception than with atrophied and redundant alert levels continuing as they are.  I'd prefer to take the PR, with a minor amendment noting the hazard caused by unrecognized_name(112).  Clients that intend to accept TLS 1.2 and lower probably have to ignore warning alerts until they see that the server is doing TLS 1.3 or higher.
>
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