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Re: [nsp] known networks for broadcast ping attacks
From: Systems Engineer <snash () lightning net>
Date: Wed, 30 Jul 1997 17:21:12 -0400

Well I happen to know the writer of "smurf.c" and he is really pissed at
how his exploit for this attack has been passed around like candy,  then
again,  he gave it out publically on the IRC.  This bug is exactly like
the one that "pepsi.c" exploited.  Little kids will have their fun with
it, realize that it is dumb and that people are patching themselves
against it, and it will die.
In the meantime ,  I did understand how it works,  just explained it a
little off :).

Netstat Webmaster wrote:

On Wed, 30 Jul 1997, Systems Engineer wrote:

Actually people are making it seem that the entire MAE is sending
you an
echo.  No one is mounting an attack from there,  they are just
making it
look like it is coming from there.

Well thats not entirely true.  In effect the victim is indeed being
'attacked' by MAE machines on that network.  Look at it like this:

evil.com -> generates packet with forged address as
(victim.com(icmp_echo)) -> destination for spoofed packet (25 .255
broadcast addresses).

From here... all 25 network's broadcast address pass the icmp with
forged address on to all machines using that network.  Each machine
replies as:

abused.net.com (echo_reply) -> victim.com
abused2.net.com (echo_reply) -> victim.com
abused3.othernet.com (echo_reply) -> victim.com
abused4.othernet.com (echo_reply) -> victim.com


Its a rather obnoxious attack, and its not exactly new.  Though I do
think that it will get much worse now that smurf.c has been written
is being passed around like candy.

The real problem I see with this particular attack is that there is
nothing short of blocking all ICMPs that 'victim.com' can do. At least

not that I am aware of.


webmaster () http://www.netstat.net

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Steven Nash                             ph:  (516)248-8400ext25
Systems Engineer / Network Security    fax:  (516)248-8897
Lightning Internet Services LLC      email:  snash () lightning net
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