Confusion over Physical Assets, Information Assets – Part Two
So I need to compile a list of ALL assets, information or otherwise,
NO!
That leads to tables and chairs and powerbars.
OK so you can't work without those, but that's not what I meant.
Physical assets are only relevant in so far as they part of information processing. You should not start from those, you should start from the information and look at how the business processes make use of it. Don't confuse you DR/BC plan with your core ISMS statements. ISO Standard 22301 addresses that.
This is, ultimately, about the business processes.
How to build an asset inventory for 27001
How do you know WHAT assets are to be included in the ISO-27K Asset Inventory?
This question and variants of the "What are assets [for ISO27K]?" comes up often and has seen much discussion on the various InfoSec forums I subscribe to.
Perhaps some ITIL influence is need. Or perhaps not since that might be too reductionist.
The important thing to note here is that the POV of the accountants/book-keepers is not the same as the ISO27K one. To them, an asset is something that was purchased and either depreciates in value, according to the rules of the tax authority you operate under, or appreciates in value (perhaps) according to the market, such as land and buildings.
Here in Canada, computer hardware and software depreciates PDQ under this scheme, so that the essential software on which you company depends is deemed worthless by the accountants. Their view is that depreciable assets should be replaced when they reach the end of their accounting-life. Your departmental budget may say different.
Many of the ISO27K Assets are things the accountants don't see: data, processes, relationships, know-how, documentation.
All Threats? All Vulnerabilities? All Assets?
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.