Not possible is a strong statement since it has happened twice so far. The assumption you are making is the assumption that I made, which is that the resolver would first try to lookup exactly what was requested, but that is not what it does for example, with the machines domain set to clementnt.com and the default Append Primary DNS suffix to lookups checked under thae advanced TCP/IP properties the result of an nslookup from the machine for www.apple.com is to lookup www.apple.com.clementnt.com which returns 64.94.110.11 because it does not exist. It does this before actually looking up what was typed. When I say it has happened twice, I mean that I have had 2 Blaster infected machines sending spoofed IP address request to 64.94.110.11 tcp port 80 containing the windowsupdate.com in the host portion of the html header. Removing blaster using virus tools eliminated this behavior. Jeremy Powell

-----Original Message----- From: Florian Weimer [mailto:fw@deneb.enyo.de] Sent: Friday, September 19, 2003 4:44 AM To: Jeremy Powell Cc: nanog@merit.edu Subject: Re: Interesting interaction between Blaster worm variants and Verisign DNS change

<Jeremy_Powell@sbcss.k12.ca.us> writes:

...

I think that an interesting interaction involving:

1) Blaster worm DDoS attack against windows update. 2) The default action of Windows 2000 and XP computers to automatically append the domain name under "Network Identification" or the suffix search list to DNS lookups. 3) The number of non-existent domains that exist in the above settings. 4) The change that Verisign made so that all non-existent domains resolve to 64.94.110.11

is the cause of the DDoS attack that Verisign is experiencing.

This is not possible. There's a NS entry for windowsupdate.com, which overrides the wildcard A record (in standard zone files, wildcard records are suppressed as soon as an RR for the domain exists, even if the types don't match).

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