Tuesday, December 9, 2008

Spamalytics Show Spam Doesn't Pay

Originally uploaded by cursedthing
This is the second in my series of posts about talks I enjoyed at ACM CCS. The first was here.

As some of you may know, my master's thesis involved creation of a spam-detector based on the workings of the human immune system. Forgoing modesty, I'll say that my system was pretty cool (I even got slashdotted) but I couldn't see myself doing spam research forever -- there's only so many times you really want to stand up in front of a room full of academics and try not to make viagra jokes.

I digress. But when I saw the paper entitled "Spamalytics: An Empirical Analysis of Spam Marketing Conversion" on the program, I knew which track to choose for that session.

They wanted to get some numbers showing click-through rates on spam, to see how much money spammers really are making nowadays, and how many people were seeing those emails. Obviously, the spam kings aren't inclined to be cooperative on this front, so they had to get creative. How they got the numbers is somewhat interesting in and of itself: They broke in to the Storm botnet and subverted some Storm controllers so a number of the bots would send out spam altered to use links they could track. The text for these email advertising campaigns remained the same; they only changed the links.

The question did come up as to whether this was ethical, as the test did involve unwitting human subjects, but they asserted that these people would have gotten the spam anyhow, and at least their links were malware-free.

Three campaigns were chosen as the focus of their study: one was a standard pharmaceutical campaign. I'm sure you're all familiar with those. The second and third were postcard and April fools' messages designed to infect more computers with the botnet software. Self-propagation for Storm.

I highly recommend you check out their paper for the detailed results, but the things I found most interesting were as follows:

(1) Very little mail actually got through to the recipients.

Using dummy addresses on popular webmail servers and an email hidden behind the popular Barracuda spam-filtering appliance, they found that less than 0.005% of mail got through in most cases. Messages were either dumped into a spam folder, or 75% of messages appeared to be dropped by the servers before delivery was even completed. This is likely due to blacklisting at the server level.

(2) Very few users visited the sites in question

(3) Some people did "infect" themselves by clicking the postcard/april fools site

(4) Many fewer people ordered pharmaceuticals. In fact, so few people did that it's unlikely that the campaign could have made money!

The final conclusion was really the most fascinating one: they gauge it as highly unlikely that the pharmacy site could have made any money given the costs of renting the botnet to send spam. In fact, they guess that spam sending would have to be 20 times cheaper for the pharmacy site to make a profit!

Could it be that spam doesn't pay?

The authors suggest that the pharmaceutical spams must be sent by the owners of the botnets (who thus wouldn't have to pay the rental cost), but I propose an alternate theory: that the only people making money from spam are the people who get paid to run the botnets. Those renting don't know that they won't make money, and the botnet owners sure aren't going to tell them. No, they'll just keep sending low-profit spam to keep up illusions that there are fantastic profits to be made (otherwise why would people send them, right?).

Maybe if I'm lucky, I'm right, and eventually the would-be spam senders will notice and stop paying exorbitant prices for botnets. But I'm afraid I don't hold out too much hope. Still, a very interesting paper, with some very interesting results!

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