Re: SMTP in distributed DOS

[I Am Not An Isp <patrick () ianai net>]

At 11:04 AM 2/20/00 -0800, Dirk Harms-Merbitz wrote:

>We are currently seeing this first hand: Our real mail.power.net is
>at 207.151.19.8. The attacker is sending individualized emails with
>faked headers that contain "mail.power.net (unverified [209.26.14.22])".
>
>The recipient computers are dumb enough to send their bounces to
>the real mail.power.net.

This is the problem - a mail server stupid enough to send a bounce to an 
unverified host name, instead of the connecting IP address.


>This is a DOS because the innocent mail server a) gets millions of
>bounces and b) might get black listed on various "anti-spam" lists.

What anti-spam list maintainer would add an unverified host name in a 
header?  Especially when the IP address does not match the hostname?


>Dirk

TTFN,
patrick

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