Re: True definition of Intrusion Prevention

[George Capehart <gwc () acm org>]

On Tuesday 30 December 2003 08:05 am, Gary Flynn wrote:
> Teicher, Mark (Mark) wrote:
> > What is the difference between Intrusion Detection, Intrusion
> > Prevention at the high level.
>
> Having the ability to block a detected attack instead of just
> reporting on it.

That's not intrusion *prevention*, it's intrusion *blocking*.  ;-)

I'm being pedantic here for two reasons:
a) I think the definition you have provided is the one that the 
marketeers implicitly use, and 
b) *blocking* an attack in process is */not/* the same as preventing an 
attack in the first place.  

An attack is */prevented/* if it doesn't or can't happen.  There are two 
broad classes of means of preventing attacks:
a) take out the attacker(s) before they attack or
b) harden the target such that it is not vulnerable to the attack.

Don't get me wrong, I don't have a problem with "intrusion blocking" if 
it is successful . . . that is, if the attack is detected in time and 
the appropriate "blocking mechanisms" are available.  I'd just rather 
call a duck a duck . . . ;-)  I think it is possible to build an 
"intrusion blocking device."  Intrusion prevention is a process.  
(Apologies to Bruce Schneier ;-)  )

I wouldn't have taken this up, but I think it is more important to make 
the distinction between "blocking" and "prevention" than is made in the 
hype.  They just aren't equivalent.  Preventing an attack means that 
action has been taken to keep the attack from happening.  Blocking an 
attack means that the attack has been launched and one hopes that one 
has all of the mechanisms in place necessary to keep the attack from 
succeeding . . .

My $0.02 USD.

Best regards,

George Capehart

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