Re: Concepts: Security and Obscurity

[Michael Rash <mbr () cipherdyne org>]

On Apr 17, 2007, Craig Wright wrote:

> Hello Justin,
> In some cases it may aid, but there is still a cost of implementing
> this. My argument is that there is no significant quantifiable gain to
> security through the implementation of a layer of obscurity. 

I think part of the confusion surrounding this whole discussion is that
I'm not sure we all agree on a good definition for what "obscurity"
means in the context of computer security.  If we can agree on a
definition, then I think we could start to test the statement above.

If one accepts the dictionary definition of "obscurity" as "the
condition of being unknown", then the term could be applied to an awful
lot of things in the computer security world.

Would you argue that passwords (taken generally) add an important
measure of security to various software?  If so, then why do they not
qualify as something in "the condition of being unknown"?

--
Michael Rash
http://www.cipherdyne.org/
Key fingerprint = 53EA 13EA 472E 3771 894F  AC69 95D8 5D6B A742 839F


> This is a valid hypothesis in the support of a proposition that security
> is improved somewhat through obscurity, though I still fail to see the
> proof of this. It would make a good experiment however.
>
> I do not believe that the survival of a system would be significantly
> impacted through this type of change. Many ports advertise themselves
> (esp. the public ones) and it is limited to services that are in
> themselves a "secret". For instance, it would not be feasible to place
> an internet SMTP server on TCP 10,025. You would not get any mail.
>
> In the case of a SSH protocol I do not see that the prevalence of
> threats from worms is significant enough to impact the survival time of
> the host. 
>
> Regards,
> Craig
>
>
>
> 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
> GPO Box 2551 Sydney NSW 2001
> Fax +61 2 9993 9497
> www.bdo.com.au
>
> Liability limited by a scheme approved under Professional Standards Legislation in respect of matters arising within 
> those States and Territories of Australia where such legislation exists.
>
> The information in this email and any attachments is confidential.  If you are not the named addressee you must not 
> read, print, copy, distribute, or use in any way this transmission or any information it contains.  If you have 
> received this message in error, please notify the sender by return email, destroy all copies and delete it from your 
> system. 
>
> Any views expressed in this message are those of the individual sender and not necessarily endorsed by BDO Kendalls.  
> You may not rely on this message as advice unless subsequently confirmed by fax or letter signed by a Partner or 
> Director of BDO Kendalls.  It is your responsibility to scan this communication and any files attached for computer 
> viruses and other defects.  BDO Kendalls does not accept liability for any loss or damage however caused which may 
> result from this communication or any files attached.  A full version of the BDO Kendalls disclaimer, and our Privacy 
> statement, can be found on the BDO Kendalls website at http://www.bdo.com.au or by emailing administrator () bdo com 
> au.
>
> BDO Kendalls is a national association of separate partnerships and entities.
>
> -----Original Message-----
>
> From: listbounce () securityfocus com [mailto:listbounce () securityfocus com]
> On Behalf Of Justin Lintz
> Sent: Tuesday, 17 April 2007 10:55 AM
> To: security-basics () securityfocus com
> Subject: Re: Re: Concepts: Security and Obscurity
>
> I am jumping in late on this and don't know if this was brought up
> already so I apologize in advanced if it has... but what about worms
> and that are set to scan networks looking for services on specific
> ports?  If you change the default port for a service, that alone could
> save your machine from being compromised in a 0-day exploit from a
> worm that only checks for the service on the default port.
>
> - Justin Lintz