Re: What's wrong with application whitelisting?

["Basgen, Brian" <bbasgen () PIMA EDU>]

Lewis,

 AV vendors have been talking about white listing for a long time. In theory, desktop white listing is an interesting 
idea, but implementing this is challenging, maintenance intensive, and context specific. 

 Take your example of a border firewall with a default deny. How many rules are necessary for most large institutions? 
Considering a dedicated border firewall, we are likely looking at a very limited and relatively straight forward rule 
set. By contrast, how many applications need to be white listed? Start with just Windows XP -- how many applications 
are part of the OS? How many applications are in use throughout the institution? How many different versions, etc?

 White listing is likely using application checksums, which means any time a program is modified, updated, etc, the 
checksum changes. Thus, how will program updates work, particularly updates for uncommon applications on your network? 
How can an AV vendor manage the process of white list updates centrally? How would the exceptions model work: how much 
control do you give to the end user to make exceptions? How could a white listing system be flexible enough to respond 
to computer changes, but rigid enough to detect bad changes? 

 A well architected border firewall will not likely change too often, because core infrastructure is relatively stable. 
The desktop of an end-user, particularly faculty, changes relatively frequently. Thus, how can white listing 
effectively manage change? 

~~~~~~~~~~~~~~~~~~
Brian Basgen
Information Security
Pima Community College
Office: 520-206-4873

From: The EDUCAUSE Security Constituent Group Listserv [mailto:SECURITY () LISTSERV EDUCAUSE EDU] On Behalf Of Watkins, 
Lewis
Sent: Monday, April 05, 2010 11:23 AM
To: SECURITY () LISTSERV EDUCAUSE EDU
Subject: [SECURITY] What's wrong with application whitelisting?

Colleagues,  Please help me understand something, that I have been trying to make sense of for awhile and just don't 
get.   What's wrong with "application whitelisting"?   As best I can tell, application whitelisting has very low 
penetration in higher education, and I simply do not understand this.   There must be issues and dynamics of which I am 
unaware to explain this.   My confusion is based on the following:

-  Security professionals seem to agree that anti-virus software is no longer working.   No single product does the 
job, and it is not feasible to run multiple products on each device.
-  Any executable that anti-virus software will stop should also be stopped by a whitelist, since the application would 
not be on the approved list.
-  Zero-day attacks are a major threat.   Anti-virus is particularly bad at stopping zero-day attacks.   Application 
whitelists are particularly good at stopping zero-day attacks. 
-  Universities use whitelisting on firewalls (i.e. we don't shut down just the ports that prove themselves to be bad - 
we open only those that are needed. )
-  Universities use whitelisting for people (i.e. we don't let everyone in the world have an account until they prove 
to be bad.  We maintain a list of approved users.)
-  However, universities use blacklisting for applications.   We tend to allow any application that can find its way 
onto our desktop computers to run.   When a program proves to be bad, we spend lots of labor and effort re-imaging the 
computer - then we do it again later.    To the extent that application whitelisting would help prevent this, costs 
would be reduced and IT could concentrate more on value added efforts.
-  We have many bots and Trojans infecting computers and do not seem to have solid solutions for preventing these 
infections.   If using whitelisting, even if a rogue program finds its way onto a person's computer, it will not 
execute.    I've seen improved network monitoring proposed as a strategy so infections will be identified and stopped 
more quickly based on traffic analysis.  This is good, but would it not be better just to prevent the malware from 
executing to begin with?
-  Much of the malware that finds its way onto our computers does so without the user's knowledge.   A whitelist would 
prevent these from executing - thus protecting the user from doing harm without intent or knowledge.  This could 
prevent us from attacking our neighbors at the next desk and other universities and institutions.

There is no doubt that we in higher education have improved significantly over the past decade in the area of 
information security.  However it seems the stakes are higher than ever and our threats and adversaries are evolving 
very rapidly.   We need new some strategies.   

Thanks - I appreciate your insights, comments, and thoughts.   Also, please let me know if the base assumptions above 
are incorrect.   This is something I really do want to understand.

    Lewis Watkins, CISO - University of Texas System
    lwatkins () utsystem edu


 

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Lewis Watkins, Chief Information Security Officer
The University of Texas System
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