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List:       nanog
Subject:    Re: [nsp] known networks for broadcast ping attacks
From:       "Alex.Bligh" <amb () xara ! net>
Date:       1997-07-31 8:32:22
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> At 7:56 PM +0100 7/30/97, Alex.Bligh wrote:
> >Urm, 192.41.177.255 is the MAE-East LAN ?! Are you saying attacks are
> >being mounted from here or people are attacking this LAN (not
> >sure which is more worrying)
> 
> The LAN is being used indirectly to attack another network.  Pings are
> spoofed as originating from the machine that is being attacked and sent to
> the broadcast address on another network.  This causes every machine on the
> receiving network to send an ECHO_RESPONSE to the machine being attacked,
> esentially creating a huge multiplying effect on a ping flood attack.
> 
> Apparently, the MAE-East LAN is one of the networks that attackers are
> using to flood other hosts.

Right. Well that's how I read it too. And just to make sure this thread
is indeed operations related, I'll make the following points:

1. Send a Cisco enough (a thousand a second) ICMP ECHO REQUESTS, and
   it takes CPU to 99% and drops all BGP sessions. Tested on a C7010.

2. Various routers on MAE-East have been mysteriously clearing all their
   BGP peers over the past week or two.

3. The attack mentioned causes a lot of ICMP ECHO REQUESTS to be sent
   to Cisco routers on MAE-East.

Are these facts by any chance related? I think we should be told. Or,
urm, find out. On with that logging ACL.

Alex Bligh
Xara Networks

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