.zip,.exe attachments and spam assassin

[Michael A. Peters]

I've gotten a ton of viruses today - there seems to be a worm lose
again.

I've come to the realization that I have never ever received a zip
attachment from someone not in my address book that I actually wanted,
so I would like to set a spam assassin rule to mark mail with a .zip
or .exe with a high spam score (my address book is white listed)

Anyone know how to do this off hand?

Another possibility would be a procmail rule - I use procmail to filter
my mail - but since spamassassin already knows about my whitelist, I'd
rather do it in spamassassin.