Date: Wed, 12 Jan 2011 11:36:34 -0800 (PST)
From: Vic Vandal <vvandal@...l.com>
To: full-disclosure@...ts.grok.org.uk
Subject: Re: Getting Off the Patch

While this idea may work in small shops, it won't scale to large ones. 
There are something like 800 heterogeneous servers where I work.  Small 
clusters of like-purpose servers are allocated to hosting many different 
processing components that make up the enterprise architecture.  Applying 
purpose-specific hardening is a goal, but one that is extremely difficult 
to achieve and then maintain.  And at the end of the day if you have a 
server cluster hosting MS-SQL or Oracle or Apache or IIS or whatever, AND 
only the necessary listening services are on, AND there is filtering to 
allow specific source and destination traffic, IF there's an identified 
vulnerability in any of those available services the machines must be 
patched to mitigate system and data risk.

Even with services/daemons/etc. that aren't used and have been disabled, 
you can't rely on them remaining that way.  Some newly installed component 
could require starting them up, or some Sys-Admin could make a 
configuration mistake and start up some vulnerable service(s).  So if 
there is software installed on a system and that software has a known 
vulnerability and an available patch, any smart resource owner is going to 
mandate that the patch be applied to mitigate "potential" risk.  If they 
don't and the system and/or data is compromised, that resource owner might 
have a hard time explaining how due diligence was exercised to absolve 
themselves and the organization of any data breach or service delivery 
liability.

As for having to spend a lot of cycles testing patches, those days of half 
of the patches being applied breaking something are long gone.  The risk 
still exists, and maybe one or two out of every hundred operating system 
or core software patches does break something.  Vendors have gotten a LOT 
better about releasing reliable patches.  I say this as an InfoSec 
engineer who has been playing this patching game for 20 years.  But what 
about that small percentage of patches that does break something?  For 
mission-critical servers any organization worth its salt has a Dev, QA, 
and Production server environment.  You roll out the patches to Dev, and 
make sure nothing breaks while the developers are working daily in that 
environment.  Then you roll to QA and have someone test any app that could 
potentially be impacted by the patch(es) deployed.  By the time you roll 
the patches to Production, the risk of an outage is almost nil.  And for 
the workstation environment, create a pilot group for patch deployments. 
Deploy patches to their machines, see if anything breaks, and if nothing 
does you then deploy the patches safely to the entire organization.

As for the cost of deploying patches and the time it takes, automated 
patching tools are quite mature and robust these days.  It takes a 
security administrator, server administrator, or desktop administrator 
mere minutes and a few mouse clicks to deploy patches to hundreds or 
thousands of machines.

The other side of this patching coin is being audited.  Many organizations 
are mandated to have independent security audits of their infrastructure 
performed.  Those organizations and others may also have business partners 
who want audit verification of how vulnerabilities are being mitigated. 
And where an independent audit report shows that an organization isn't 
applying patches for countless vulnerabilities on scores of systems, you 
can bet that the concept and practice of patching will be embraced very 
soon thereafter.

Just for clarity I'm not saying the proposed idea has no value.  I'm a big 
fan of system hardening via various means.  If you're not running a 
vulnerable service or it's not available to untrusted machines or users, 
the chances of it being compromised are obviously diminished greatly.  But 
you shouldn't rely on that situation remaining static, and the smart move 
is to patch vulnerable software or remove it from the system altogether if 
it isn't needed.  Obviously removal isn't an option when it comes to 
operating systems.  You could replace them with some B1 certified security 
level system, but you're not going to be able to run a lot of common 
business apps successfully on such an architecture.  And even if you could 
those apps could have vulnerabilities and need to be patched.  Sandboxing 
has value, but it doesn't supplant patching in my professional opinion.

I do know a way to do away with patching - have software developers stop 
writing crappy code that doesn't do good input validation (cough).  Of 
course that is a nirvana not likely to be seen in our lifetimes.

Wow, did I just write an article damn near equal in length to the InfoSec 
Island one posted that started this thread?  Either I have free time to 
spare or I'm really into the concept of patching known vulnerabilities. 
Unfortunately for me it's the latter.

Peace,
Vic

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