Firewall Wizards mailing list archives

Re: PCI DSS & Firewalls


From: AMuse <amuse () foofus com>
Date: Thu, 02 Apr 2009 11:58:53 -0700

Isn't the point of pen-testing to take up an attackers' perspective and hit all your defenses to see if you missed something or misconfigured something? I mean, unless you're the only person who set up 100% of your infrastructure, how are you to know that someone didn't accidentally leave telnet open? If you didn't write 100% of the webapps your company is using, how are you to know they don't have SQL injection flaws?

Marcus J. Ranum wrote:
Frank Knobbe wrote:
>> I also agree with Marcus that it's the Pen Tester's Employment Security
Act..

Wouldn't you want to test your security controls periodically?

Of course. That's part of good engineering. But...

Good engineering says that you have structural elements that
should have various known and measurable capabilities. In
security, that would mean that you have a security design,
and that design would call out specific properties of how
the system should work and should behave. Yes, you'd want
to test to verify that the system was still working in
accordance to its design.

That's exactly the opposite from periodically flinging
poop at it and seeing if it still smells like a rose
afterward.  Pardon my metaphor. :)  The idea of pen testing
IS TO SIMULATE AN ATTACK
well, your design ought to be such that no known attacks
will work against it. Put differently
THERE SHOULD BE NO KNOWN POINT OF ATTACK
If that's the case, then simulating an attack, using
all the known tricks in the bad guy's arsenal - is
utterly stupid. If what you were to do was to perform a
top to bottom verification that the system's implementation
was still in accordance with its specifications
then that's a "design review" coupled with an "implementation
test" or "design oriented implementation review" - doing
that sort of test would require a completely different
set of tools from what a pen tester uses, and it would
be performed with a system design document in hand, from
the "inside" toward the "outside."

Of course the bad guys are innovating too, and it's very
much worth keeping track of what they're up to and updating
designs and plans accordingly. But - again - that doesn't
need pen testing; that needs periodic design reviews in
the face of newly uncovered forms of attacks. I.e.: your
system should be proof against SQL injection attacks; and
your code should have been carefully reviewed and tested
to be in accordance with that design. If you want to do a
"pen test" at that point, they should be looking at your
source code, not badpacketing you or whatever silliness.
If the bad guys invent a new form of attack, then it's
time to review your design to see how it resists that
form of attack: defend against general CATEGORIES
not SPECIFIC INSTANCES.

The pen testing paradigm is intellectually bankrupt.

mjr.
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