A new method of spamming is being used by the typical Viagra/Levitra/Cialis crew.
First, you get an email like this inviting you to join a Yahoo group:
Cute. This is a form of reputation hijacking, where a completely legitimate service (Yahoo Groups) gets right through all spam filters.
Clicking “Join this group!” gets you to the standard Yahoo Groups page. Except it’s got an ad for spammed prescription meds.
Of course, the purpose is not to get you to join any group (or as a phishing attempt, as some might think). It’s simply a ruse to display an ad for spammed prescription drugs.
If you join, of course, you’ve just given a nice free gift as well — your email address to a Yahoo Group run by spammers.
Here’s the HTML code they’re using (for fun, see if you can spot the mistake they made).
Reputation hijacking is a big part of the future of malware social engineering and spamming. Expect plenty more of the same.