The InfoSec Blog

Information Gathering and Risk Assessment

Posted by Anton Aylward

On the ISO2700 forum one user gave a long description of his information gathering process but expressed frustration over what to do with it all all, the assets, the threats and so forth, and trying to make it into a risk assessment.

It was easy for the more experienced of us to see what he was missing.

He was missing something very important -- a RISK MODEL
The model determines what you look for and how it is relevant.

What drives the RA? Need or Fashion?

Posted by Anton Aylward

A colleague in InfoSec made the following observation:

My point - RA is a nice to have, but it is superfluous. It looks nice
but does NOTHING without the bases being covered. what we need
is a baseline that everyone accepts as necessary (call it the house
odds if you like...)

Most of us in the profession have met the case where a Risk Analysis would be nice to have but is superfluous because the baseline controls that were needed were obvious and 'generally accepted', which makes me wonder why any of us support the fallacy or RA.

It gets back to the thing about the Hollywood effect that is Pen Testing. Quite apart from the many downsides it has from a business POV it is non-logical in the same way that RA is non-logical.

All Threats? All Vulnerabilities? All Assets?

Posted by Anton Aylward

One list I subscribe I saw this outrageous statement:

ISO 27001 requires that you take account of all the relevant threats
(and vulnerabilities) to every asset - that means that you have to
consider whether every threat from your list is related to each of
your assets.

"All"? "Every"?
I certainly hope not!
Unless you have a rule as to where to stop those lists - vectors that you are going to multiply - are going to become indefinitely large if not infinite. Its a problem in set theory to do with enumberability.

See
http://infosecblog.antonaylward.com/2010/05/19/the-classical-risk-equation/
for a more complete discussion of this aspect of 'risk'.

See
http://www.bloginfosec.com/2010/08/23/why-the-risk-threats-x-vulnerabilities-x-impact-formula-is-mathematical-nonsense/
in which Jeff Lowder has a discussion of the "utility value" approach to controls

Because its the controls and their effectiveness that really count.

“Impact” is not a Metric

Posted by Anton Aylward

I never like to see the term 'impact'.
Its not a metric.

I discuss how length, temperature, weight, are metrics whereas speed, acceleration, entropy are derived values. In the same sense, 'impact' is a derived value - "the cost of the harm to an asset". The value of an asset can be treated as a primary metric, but how much it is "impacted" is a derived value.

This is the same kind of sloppy thinking, the same failure to identify tangible metrics as we see when people treating 'risk' as if it were something tangible, never mind a metric!