RE: Concepts: Security and Obscurity

[<jay.tomas () infosecguru com>]

You make a lot of assumptions about how people interpret security through obscurity what it means and what costs are 
associated with it. I think it gets mentioned every time I post that no one layer will protect you, but a combination 
of them will better defend you. The idea is to slow the attacker, identify you are under attack and then remediate the 
exposure. No defense will protect you indefinitely. Also just because people don't implement a concept correctly 
doesn't mean the underlying premises are not valid.

To your points on cost it evident that you do not nor have you ever participated in the military, law enforcement or 
other profession that could endanger your life. You can monetarily define how much a server costs, but you can't put a 
price on human life. If a credit car processor's has data loss leading to identity theft they have to pay folks Credit 
Monitoring for a year. If government , military or law enforcement shirk then people die.

It's like saying don't wear camouflage because it can't stop a bullet.

 I have served in the military and know what its like to defend, protect life. I currently work for a bank, so I also 
know about cost benefit analysis . I just disagree with such a strong biased outcry against   particular security  
approaches. "All" solutions should be evaluated based on environment, and particular implementation 
variables/requirements.

There is a difference between risk and security. Risk can be calculated by on variety of models incorporating cost, 
loss exposure. Security is  more absolute. You are either secure or not secure. Same goes for Threat vs. Vulnerability. 
Threats may or may not exist or have the capability to cause exposure. If you are vulnerable you are vulnerable 
regardless of what impact.

Jay

----- Original Message -----
From: Craig Wright [mailto:Craig.Wright () bdo com au]
To: krymson () gmail com,security-basics () securityfocus com
Sent: Wed, 11 Apr 2007 08:50:45 +1000
Subject: RE: Concepts: Security and Obscurity

Hello,
I have at no point claimed absolute security measures or cost
structures. Excuse me, but your idea that economics and finance has
nothing to do with security is pure head in the sand ignorance. Security
is a cost function - pure and simple.

Would suggest that you think about the real costs and gains in
obscurity. This is both short and long term. You may be thinking of just
your role now and no more. This is a view that ignores the total
economic costs. It also ignores the requirements of a control function.

Obscurity is not a control that may be meaningfully measured and
maintained. The effectiveness is reliant on an unknown quantity.

Please demonstrate your hypothetical controls. Stating your hypothesis
in an intestable way does nothing to further the argument.

Now the issue with security through obscurity is that people take the
initial value of the control to be the entire value of the control over
time using a discrete risk model. However, this type of risk function is
clearly a poisson model. There is research on this (other than my own) -
[1], [2], [3], [4]. I could quote several hundred references on the
scientific evaluation of risk models. The Cost function for obscurity is
exponential and the protection/ risk model is poisson.

Now what does an exponential cost with a poisson gain give us? It means
that there may be some preliminary gains - but at an uncertainty that
gives a wide prediction interval at any reasonable level of confidence.

Next, the exponential model grows faster than the poisson models
decreases. This means in time the cost of the control will exceed the
benefit. The requirement is that the obscurity based control needs to be
updated to remain effective and thus requires added input and thus cost.

Risk is quantitatively calculable using hazard and survival functions.
Even taking for the maximum likely benefit, obscurity is not cost
effective.

Craig

References

[1] J. Herrin (1), B. J. Dempsey III " WEB-Enabled Medical Databases: a
Threat to Security?"
Methods of Information in Medicine 2000 39 4: 298-302.
Zeitschriften  -  Methods of Information in Medicine  -  Archive  -
Issue 4/5 2000

[2]Manish Karir John S. Baras "LES: Layered Encryption Security"
Center for Satellite and Hybrid Communication Networks
Department of Electrical and Computer Engineering & Institute for
Systems Engineering
University of Maryland, College Park, MD 20742, USA

[3] Michael K. Bond "Understanding Security APIs" University of
Cambridge
Computer Laboratory Jan 2004

[4]Giovanni. Vigna, "Recent Advances in Intrusion Detection: third
international workshop", RAID 2000, Toulouse

[5] Lennart Erixon " Even the bad times are good: a behavioural theory
of transformation pressure " Cambridge Journal of Economics,
doi:10.1093/cje/bel035

And a little further related reading for the techniques:

Bertoin, J. Levy Processes

Bunday, B. D. An Introduction to Queueing Theory

Freund, R. J. and Wilson, W. J. Statistical Methods

Hall, P. The Bootstrap Estimate and Edgeworth Expansion

Hills, J. (ed.) New Inequalities: the Changing Distribution of Income
and Wealth in the United Kingdom

Hughes, B. D. Random Walks and Random Environments: vol. 2, Random
Environments

Kelly, F. P., Zachary, S. and Ziedins, I. (eds) Stochastic Networks:
Theory and Applications

Kleinbaum, D. G. Survival Analysis-a Self-learning Text , p. 375

Robertson, B. and Vignaux, G. A. Interpreting Evidence: Evaluating
Forensic Science in the Courtroom

Schervish, M. J. Theory of Statistics

Sen, P. K. and Singer, J. M. Large Sample Methods in Statistics, an
Introduction with Applications

Zaman, A. Statistical Foundations for Econometric Techniques




Craig Wright
Manager of Information Systems

Direct +61 2 9286 5497
Craig.Wright () bdo com au

BDO Kendalls (NSW)
Level 19, 2 Market Street Sydney NSW 2000
PO Box 2551 Sydney NSW 2001
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-----Original Message-----

From: listbounce () securityfocus com [mailto:listbounce () securityfocus com]
On Behalf Of krymson () gmail com
Sent: Wednesday, 11 April 2007 12:53 AM
To: security-basics () securityfocus com
Subject: RE: Concepts: Security and Obscurity

I really think you just like hearing yourself talk. And while you spout
some common axims and economics 101 terms, they don't mean much to this
topic. Your whole fourth paragraph, while we can agree with what you
said, has nothing to do with the topic.

You assume that there are absolute security solutions instead of the
incremental security that can be experienced by pairing up some forms of
obscurity. I'll throw in my own axims that "security is not a
state/product but rather a process/layering" and "there is no silver
bullet to security."

You also assume that gains are minimal with all obscurity, and that they
have added difficulty and lost productivity. That is not necessarily
true.

If I have two forms of obscurity that both cost the same but together
the total cost is less than the asset and thus worthwhile, I can't use
them? I have to look for something that costs less than both those
obscurities that secure the asset perfectly?



<- snip ->
What is forgotten is that there is an economic/financial cost to all
controls.

A control is only effective if the cost of the control provides more
utility than not having the control. Thus a control that provides some
security at a cost that is greater than another control is ineffective
overall.

Security by Obscurity is an ineffective control. The gains are minimal
in economic terms. The cost however is more than the pure cash/money
costs. The additional losses to productivity and added difficultly in
maintaining secrecy does not provide the required level of gains to
offset the costs and thus creates a dead-weight loss in economic terms.

Thus security by obscurity is no security as the costs in real economic
terms do not bring benefit.

It is of no use to spend $1,000,000 protecting a $1,000 asset. This is a
loss and thus it is not a decision that provides security as the loss
exists even before the system goes live.