On Sat, 31 Mar 2007, Mikael Abrahamsson wrote:
On Sat, 31 Mar 2007, Gadi Evron wrote:
In this case, we speak of a problem with DNS, not sendmail, and not bind.
The argument can be made that you're trying to solve a windows-problem by implementing blocking in DNS.
Next step would be to ask all access providers to block outgoing UDP/53 so people can't use open resolvers or machines set up to act as resolvers for certain DNS information that the botnets need, as per the same analysis that blocking TCP/25 stops spam.
So what you're trying to do is a pure stop-gap measure that won't scale in the long run. Fix the real problem instead of trying to bandaid the symptoms.
IMHO, Windows will always have some 0-day appearing every quarter - whether it be in XP or Vista. Or it will be in Apache, or it will be in Sendmail or it will be in some other app. So if taking a 10,000 foot view, apps will always have 0-day holes that are abused. Nowadays, the latest vector is fast-flux. I think that closing that vector via fast closure of a particular domain name is something we should tackle. True, the baddies will find some other vector. But that doesn't mean we should ignore this one. -Hank
-- Mikael Abrahamsson email: swmike@swm.pp.se