Re: Concepts: Security and Obscurity

["Craig Wright" <Craig.Wright () bdo com au>]

"It is impossible for you to make that assertion for all environments and situations" Of course it is not. This is what 
statistical inference is all about. It is a complexity calculation and not as difficult as you believe. As for the next 
point, I have to believe that you misunderstood the sentance as that is the only way that your response can make sense.
 
This idea that experimentation has nothing to do with the real world is sad. You sit typing on a machine that is 
developed through advances in mathematics and pure theory (and some of what is the theory can not be experimentally 
tested in the quantum physics used to develop processes to tunnel electrons that make processors work) and state theory 
has no part in the real world. How sad.
 
"I'd love to see such a study.  It does not exist. " HUH! Do you read any academic journels? IEEE, ACM... I suggest 
that you do a search before stating this.
 
This idea that your logs are not full of junk as you have obscurity? Where did this come from? Please?
 
Stating that I agreed with you in terms of obscurity is not the case in terms of a low level of methematical knowledge 
in the IT and hacker community. The knowledge is open and available. It is not obscure. There is a clear difference to 
obscurity and ignorance. Also, this is a threat not a securty feature.
 
"It would take you forever to assess all 65,535 TCP and UDP ports" As for the how longs, scanning externally generally 
takes 2-3 hours of time setting up. A weekend to run and a night to run the results through an inference engine. 
Clients do not pay for computer time - so minimal. Ports and addresses are randomised and if I was not doing this for 
money I would spread it over a month, but either way I get about 1 in 10 for being accurately detected.
 
I think that you need to come to understand the real cost of a control. Economic cost is not finacial cost, but it is 
the one that matters most. I would suggest that you read up on what the two terms are. Your comments on costs 
demonstrate that you do not understand economic cost. This is not a cash cost. There is more to it.
 
Craig



Craig Wright
Manager of Information Systems

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

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________________________________


From: listbounce () securityfocus com on behalf of levinson_k () securityadmin info
Sent: Fri 13/04/2007 1:42 PM
To: security-basics () securityfocus com
Subject: Re: RE: Re: Re: Re: Concepts: Security and Obscurity





> Obscurity does not work.

It is impossible for you to make that assertion for all environments and situations.  "Obscurity" includes a lot of 
different things.  You cannot do a risk assessment in an ivory tower without knowledge of the specific environment, 
threats, etc.


> Here we get to the real point. Obscurity is not the factor that is
> increasing the security of the site. You have a confounding variable in
> this model. That is monitoring.

Exactly.  It is pointless in the real world to try to say that obscurity never works, because methods of obscurity are 
often inexplicably tied to other benefits.  So maybe you're using a purely theoretical model that doesn't apply in the 
real world.


> To test the effectiveness of obscurity scientifically you have to remove
> or make account for the confounding variables.

This kind of pure theoretical study would have no value in actual real world security.


> In a test that is determined scientifically and without bias,
> the results show that obscurity does not reduce risk and is thus not a
> benefit.

I'd love to see such a study.  It does not exist.  Obscurity often reduces certain risks (script kiddies, viruses, 
etc.), while doing nothing to increase other risks (some determined attackers).  This is what you call your win-win 
scenario. 


> When scanning a site managed by a profession 24x7 firms, with notice, I
> have rarely had them become aware of (maybe 1 in 10) the fact that the
> client is being tested.

That's because their logs are full of junk.  Because they're not using obscurity.


> It is randomised and over time and uses event
> sequence mining to reconstruct the ruleset (i.e. maths).

I would love to see you do such a low and slow scan of a site that uses a nonstandard TCP/IP port and something like 
port knocking.  It would take you forever to assess all 65,535 TCP and UDP ports, certainly longer than your typical 
penetration testing engagement.  Therefore, obscurity works.

You keep arguing against obscurity by cherry picking these extreme cases of a very determined and experienced attacker. 
 Yes, some attackers could bypass obscurity, and also antivirus, firewalls, etc.  No one ever claimed obscurity would 
prevent these things.  This does not make them useless at reducing risk.  In risk assessments, countermeasures are tied 
to specific threats they are meant to mitigate.  You are intentionally taking other irrelevant threats to try to claim 
zero effectiveness of obscurity.

You also assert that obscurity is always expensive, despite many examples to the contrary.  You are making "always" and 
"never" statements that are frequently impossible to support, certainly not by cherry picking certain extreme examples.


> I do however
> guess that gets ride of much of the "hacker" community of course these
> days as it requires that SAS, SPSS, R or some other statistical package
> is used and does not rely on a tool.

So then we are in agreement that obscurity is effective at reducing certain risks.  Thank you!


> The confusion here is that you are assuming that this is the only (or
> best) method to increase log visibility and that this will find the
> attacker.

I did not. 

But it may very well be a good method to use, as it costs little or nothing.  You cannot prove that this method is 
never a useful method.  But it is easy to prove that it might *sometimes* be a useful method.

kind regards,
Karl Levinson
http://securityadmin.info