Re: Understanding Randal's answer

[Peter Scott]

I think the useful point that somehow got buried in the sand along with the 
ostrich was that security is a running battle.  You *must* take every 
opportunity to plug everything that could conceivably be a security hole, 
even if it depends upon some other layer of security being broken 
first.  Because the state of the art is such that a vulnerability for that 
other layer could be discovered tomorrow and exploited on your system 
before you've gotten a patch.  Securing a system today is like being 
Sigourney Weaver in "Alien"...