[Spambayes] Latest spammer trick stymied

Chris Lowe spambayes_discussion at cklowe.com
Tue Apr 1 10:30:40 EST 2003

T. Alexander Popiel wrote:
> If there comes to be a widely deployed tool with this sort of
> fetch-what-I-tell-you-to behaviour, then itwill get exploited
> by people wanting to do a denial of serviceattack or similar.

I'm not convinced by this.

In order to mount a good DOS attack, the attacker must effectively multiply
his bandwidth as much as possible, so his paltry broadband link can compete
with a well connected server farm.  The standard techniques are to use small
ping packets that require large, 64K responses, and to use zombies that make
continuous requests.

A URL sent in an email via SMTP represents a sizeable amount of data, and
unlike ping packets involves establishing a TCP link.

Only a fraction of the recipients will follow the URL.

Bandwidth-consuming images are not going to be downloaded by the crawler,
just text.

So I don't believe an attacker will consider spamming URLs to millions of
recipients an effective way to use his bandwidth to eat up the target's



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