[Dailydave] CVSS is the worst compression algorithm ever

[Konrads Smelkovs]

The question is not whether it is a bad metric, but whether it is a useful
one.

As a lurker on the first.org mailing list for CVSSv3 SIG, I can assure you
that there are a lot of discussions about edge cases etc. v3 is a
meaningful improvement over v2. So far, CVSS has allowed industry broadly
to triage security issues and decide if something can be addressed in next
image refresh or something that needs to be done now as an emergency, out
of band maintenance. CMU are actually active contributor to the CVSS
specification.






--
Konrads Smelkovs
Applied IT sorcery.


On Tue, 8 Jan 2019 at 16:23, Dave Aitel <dave.aitel at cyxtera.com> wrote:

> I wanted to take a few minutes and do a quick highlight of a paper from
> CMU-CERT which I think most people have missed out on:
> https://resources.sei.cmu.edu/asset_files/WhitePaper/2018_019_001_538372.pdf
> Towards Improving CVSS - resources.sei.cmu.edu
> <https://resources.sei.cmu.edu/asset_files/WhitePaper/2018_019_001_538372.pdf>
> resources.sei.cmu.edu
> SOFTWARE ENGINEERING INSTITUTE | CARNEGIE MELLON UNIVERSITY
> REV-03.18.2016.0 Distribution Statement A: Approved for Public Release;
> Distribution Is Unlimited TOWARDS IMPROVING CVSS
> It's almost as funny a read as their previous best work on how "clientless
> HTTPS VPNs are insanely dumb <https://www.kb.cert.org/vuls/id/261869/> what were
> you thinking omg?"
>
> They use a ton of big words in the paper to call CVSS out and give it a
> shellacking. Like most of you, we have extensive use of CVSS in our
> consulting practice and I've seen this stuff first hand. CVSS is of course
> just a buggy compression algorithm for taking complex qualitative data and
> then putting it on a number line. The paper has three angles here:
>
>    1. Qualitative mappings into quantitative numbers are a silly thing to
>    do, like people trying to do "social science" by using SurveyMonkey.
>    2. We're pretty sure that the compression algorithm is not, in fact,
>    putting higher risk items as bigger numbers, which is the whole point of
>    the thing.
>    3. Nobody is applying this in any sort of consistent way (which is
>    probably impossible) which is ALSO the whole point of the thing.
>
>
> It's fine to have a lossy compression algorithm that emphasizes certain
> aspects of the input signal over others, of course, but an additional
> CERT/CC critique is we have no reason to think CVSS does this in any useful
> way.
>
>
> There's definitely people in the CVSS process (who I will avoid calling
> out by name) who think ANY quantization is good. But read the paper and
> decide for yourself - because these are probably serious issues that are
> turning your entire risk org into a Garbage-In-Garbage-Out org...
>
>
> -dave
>
>
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