IDS mailing list archives

Re: Changes in IDS Companies?


From: scottw () cylant com
Date: Thu, 17 Oct 2002 18:58:16 -0700

Clint,

Excellent metaphor!  The situation is actually worse.  Every few
days, a new door is put in the building.  This door isn't
authorized, doesn't go through the architects, doesn't get
approved, it just shows up.  And, the alarm company isn't called
out to install a sensor for it.

Reality is harsh.

Regards,
scottwimer

On Thu, Oct 17, 2002 at 06:16:57PM -0700, Clint Byrum wrote:
On Thu, 2002-10-17 at 00:26, Eye Dius wrote:
In-Reply-To: <003101c27594$5de8e970$01000001 () SecurityConscious com>

- snip -

IDS vendors have not
been able to get false alarm/postive rates down to a level where
organizations would trust an IDS alert to enforce network policy.  

Nothing I've seen or read from these new vendors gives me any reason to
believe they have cured the cancer of IDS - false alarms/positives.

What are some of the big reasons for false positives? What is preventing 
new or existing vendors from fixing this problem?


This is a good question. I think we can look to other intrusion
detection systems for the answer. By that, I mean conventional physical
alarm systems.

Typically when you add an alarm system to your building, the installer
finds all of the possibly vulnerable points of entry, and protects those
with peripheral sensors such as motion detectors or glass break
detectors.

After that, the installer will consult with you on any other areas of
great interest, such as accounting, the server rooms, or maybe areas
with precious merchandise/raw materials. These are guarded with greater
physical barriers, such as larger doors, chain link fence, etc.

Then the system is setup with schedules, to allow for the expected
behaviors of arrivals and departures, cleaning, etc.

Finally, once the system is in place, the various classes of building
tenants, from janitors to CEO's, are informed of any changes to their
routines if necessary.

Now, when NIDS is installed, similar things happen. Sensors are placed
in vulnerable peripheral areas of the network, i.e. outside the
firewall, on the DMZ.. etc. And then more sensors, and maybe even the
actual NIPS are placed around critical machines such as authentication
servers and ERP systems.

Once this is done, the IDS's are tuned to allow for normal behavior, and
possibly any previously unknown problems are fixed. This usually
involves walking around and removing things like Kazaa and ICQ from
peoples' machines. ;)

So.. wait.. this sounds like we're doing things the same way.. right?
Well, we are. The problem is, the traditional security system is
handling people moving through a building. People generally walk pretty
slow, and only so many can fit in the building at one time. These people
also probably manage to trigger false alarms once or twice a year...
depending on how many of them there are, and how tight the system is.

With NIDS and NIPS, its like you're setting up a security system to
monitor and control access to a building in which 10 million people work
every day.

Ok, so with that in mind.. how do we make false positives go away? Some
things we can specify as known bad... like virus signatures and such.
Other things just look suspicious, and we have to make a judgement call
as to whether or not we're going to alert, or even shut down a
connection, based on that suspicion. Now.. how to make that judgement
call easy, is anyone's guess. :-P

-- 
Scott M. Wimer, CTO                      Cylant
www.cylant.com                           121 Sweet Ave.
v. (208) 883-4892                        Suite 123
c. (208) 850-4454                        Moscow, ID 83843
There is no Security without Control.


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