Re: [Chicken-users] OpenSSL egg option defaults poll

[Andy Bennett]

Hi,

>> [...]
>> Having said that, I'm not sure which clients on which operating systems
>> are SSL 3.0 only.
>> [...]

Having read a bit more...

I suspect (infer) that IE6 and possibly more things on Windows XP are
the client side problems.

I also suspect (infer) that the "SSL 3.0 only" (no TLS) problems are
with old web *servers* rather than a proliferation of clients other than
IE6.


> if I understand the situation correctly, almost nobody uses SSLv3 since
> it was quickly superseded by the newer TLS variants. But the initial
> connection setup is similar between SSLv2 and SSLv3, while for TLS it is
> entirely different and usually one uses the SSLv2 variant with
> additional information that TLS is supported, if the other endpoint also
> supports TLS, the protocol will then be upgraded. You can tell OpenSSL
> to support only SSLv2, only SSLv3, only TLS or all three variants
> together. But you cannot specifically exclude SSLv3 and still allow
> SSLv2 and TLS.

Thanks for the extra details.

AIUI, SSLv2 and SSLv3 are more different to each other than SSLv3 and
TLS1.0 ...but I suspect that's because I'm mostly familiar with the
"SSLv2 variant with additional information that TLS is supported".



>> [...]
>> Have you seen this article by Google about TLS_FALLBACK_SCSV?
>> [...]
> 
> Yes. Whether that security measure is supported depends on the version
> of the underlying SSL library, I think it is incorporated in OpenSSL
> 1.0.1j. I'm unsure whether anything special needs to be done to activate
> the feature.

I wonder if there's a test site that will connect to a webserver and
tell you if it supports that?


> Personally, I think the big mess of SSL/TLS protocol versions, extension
> features and cipher suites is so hideously complex by now that there
> will always be some more hidden vulnerabilities %-] For anything truly
> security critical I would try to use an alternative protocol with a less
> convoluted design and with stronger default crypto algorithms.

I agree. We'd like to run a good-and-proper SSL service but I think we'd
rather run a highly compatible service when we have a choice. This
trade-off starts to make sense when you take into consideration all the
potential vulnerabilities that exist in even the newer versions.





Regards,
@ndy

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