Re: [NSE] Script ssl-enum-ciphers should not penalize 3DES

[Daniel Miller <bonsaiviking () gmail com>]

nnposter,

There's no way we could have known this 2 weeks ago, but it sounds like
3DES in TLS has some problems. The "SWEET32" attack [1] has demonstrated
block collisions in 64-bit blocksize ciphers after 2^32 blocks (about
32GB), and decryption of small values (such as cookies) after 750GB or so.
OpenSSL is downgrading 3DES to MEDIUM and declares "triple-DES should now
be considered as “bad” as RC4." [2]

I think we should at least back out the change that artificially boosted
3DES's cipher strength. Depending on how discussion plays out with the
crypto experts over the next few weeks, we may consider adding a warning
like we do for SHA-1 certs, RC4, and other things.

Dan

[1] https://sweet32.info/
[2] https://www.openssl.org/blog/blog/2016/08/24/sweet32/

On Sat, Aug 6, 2016 at 5:14 PM, nnposter <nnposter () users sourceforge net>
wrote:

> Rob's note below is the only feedback I have received so far. As such I
> am going to commit the proposed change later next week unless anybody
> objects.
>
> Cheers,
> nnposter
>
>
> On 7/29/16 11:38 AM, Rob Nicholls wrote:
> > I'm fairly happy with that suggestion. I believe Nessus also treats
> 112-bit
> > (i.e. 3DES) keys as a "High" strength cipher.
> >
> > Rob
> >
> > -----Original Message-----
> > From: dev [mailto:dev-bounces () nmap org] On Behalf Of nnposter
> > Sent: 29 July 2016 18:10
> > To: dev () nmap org
> > Subject: [NSE] Script ssl-enum-ciphers should not penalize 3DES
> >
> > As of now, script ssl-enum-ciphers is rating cipher suites based on 3DES
> > (112-bit keys) the same as those using plain 56-bit DES.
> >
> > Given that 56-bit keys are considered easily within the reach of average
> > adversaries while 3DES keys are deemed safe at the moment, I would like
> to
> > propose that we change the rating to treat 3DES on par with 128-bit
> ciphers.
> > This position is supported by SSL Labs, which does not flag presence of
> 3DES
> > cipher suites, while rating "Cipher Strength" of such sites as "Green".
> >
> > More details at https://github.com/nmap/nmap/issues/474
> >
> > Please voice any concerns with such a change.
> >
> >
> > Cheers,
> > nnposter
>
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