[nsp] known networks for broadcast ping attacks

Wed Jul 30 20:57:34 UTC 1997

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 the 
forged address on to all machines using that network.  Each machine then 
replies as:

xxx.xxx.xxx.255
abused.net.com (echo_reply) -> victim.com
abused2.net.com (echo_reply) -> victim.com
yyy.yyy.yyy.255
abused3.othernet.com (echo_reply) -> victim.com
abused4.othernet.com (echo_reply) -> victim.com

[...etc...]

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 and 
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.

Regards,
Tripp

webmaster at http://www.netstat.net