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Re: 80/udp floods?

  • From: Wayne E. Bouchard
  • Date: Wed Feb 18 19:49:26 2004

Yes, this seems to be a common thing these days. You send udp/LAGE udp
packets and fragments to port 80 to saturate bandwidth and you combine
that with compromised hosts successively opening and closing TCP
connections to port 80 (Not a syn flood, actual connections that look
to the router in terms of packet size etc to be legitimate.) A note
that the majority of these hosts are from LACNIC and APNIC
space. (with a smattering from RIPE) I almost never see ARIN address
space used for these compromised hosts.

Most of the attacks I've seen recently have used this setup.

Easy enough to fend off except for the TCP 80 bit. For most of these
attacks, I've taken to just filtering the entire LACNIC and APNIC
address delegations at the host level for the durration of the
incident since, in the general case, my customers (the ones that
suffer these incidents) do little if any business in that region.

On Wed, Feb 18, 2004 at 02:45:14AM -0800, Scott Call wrote:
> I apologize for the potentially obvious question, but I've been through
> sf, google, etc and can't find anything.
> I have a customer that is currently getting several hundred thousand
> packets per second sent to them on 80/udp.  /etc/services lists 80/udp as
> IANA assigned for http but I've never seen a udp implementation of http so
> I'm assuming it's a sneaky DOS/DDOS of some kind.
> ACL's seem to work to catch it but I'm curious if anyone has seen this
> specific attack (80/udp) before.
> Thanks
> -Scott
> -- 
> Scott Call	Router Geek, ATGi, home of $6.95 Prime Rib
> I make the world a better place, I boycott Wal-Mart
> VoIP incoming: +1 360-382-1814

Wayne Bouchard
[email protected]
Network Dude