On Thu, Dec 23, 2004 at 12:43:31AM -0600, Ron DuFresne wrote: > My thoughts on this have centered on the point that there are too many > decent scanning and banner grabbing tools out there to make botuse port > assingments off the default any much good at obscuring the service. > > We are lucky in that most the coded sploits and POCs tend to be cheap in > that they tend to look for specifics in a very narrowly focused tunnel. > The potentials for something being crafted that is much more insidiously > inventive in determing attack vectors that might be non-norm are there. > And beaucse they remain at this time 'potential' should not be a reason or > rationale to try and place minimally effective or incomplete controls in > the security layers one uses. The IT community has been repeatedly bitten > by doing less then they know better to do due to the potential of > something not yet unleashed, say 1988 for example. >
There needs to be some differentiation between worms and exploits here. In the case of a single attacker specifically targeting a machine, then yes, I agree that a non-standard port configuration is not going to help due to such "insidiously inventive" tools as nmap and its -sV. However a non-standard port does help in the general case when it comes to a worm. The reason that we have not seen a worm search for non-standard configurations is not so much a lack of ingenuity by the authors, but more of a realisation that the time spent on scanning each target is better spent looking for other potentially vulnerable hosts with a standard port configuration. That is to say, searching each potential host for non-standard ports is inefficient and would likely inhibit the spread of such a worm. I don't have any figures to support this claim, but its hard to imagine the percentage of non-standard port configurations for any service on the internet being high enough to be an attractive target for a worm. In the end, running a service on a non-standard port at this point in time is a useful part of a layered security approach, if only to inhibit worms. -- Ben Hawkes pie.sf.net (fiver) _______________________________________________ Full-Disclosure - We believe in it. Charter: http://lists.netsys.com/full-disclosure-charter.html
