1. Victor Ivanov Spam

2. Introduction • Definition • Unsolicited bulk messages • Concerns • Server load • Garbage content

3. Types of spam • Email, IM, Skype and such • Search index spam (doorways and stuff) • Site spam (guestbooks, blog comments, forums, soc.nets, etc)

4. Email spam • 85-97% of all emails • Some techniques • Image spam • Blank spam • Bill Gates receives four million e-mails per year, most of them spam • Servers forward, receive and store unnecessary data

5. Search index spam • Doorways • Short-lived sites made for traffic collection • Traffic is sold to partner programs • Doorways for Google are often spammed further • Doorway elements • Sections of valid sites that are made to attract traffic to inexistent content • E.g. “product reviews”, be the first • This kind of spam does not directly affect any server resources (except Google’s ones), but is connected to other spam

6. Site spamming • Most often, the purpose is supporting doorways • Guestbooks, forums, etc. that have no or weak CAPTCHAs are common victims • Some intelligent tools to spam • Xrumer (around $600) • Spammers can overwhelm small sites even if they can’t break through defenses

7. How do we fight spam?

8. Email spam countermeasures • IP filtering • Restrictions on bulk email sending • Heuristic analysis of each message

9. How to fight site spam • CAPTCHA (Completely Automated Public Turing test to tell Computers and Humans Apart) • Must be either unique or updated regularly • Heuristic analysis • Remote option example - Mollom.com • Rejecting comments with either “[URL=” or “<a href=” in them

10. What we can do about index spam • Improve index filtering • Fight site spamming

11. Conclusion • Spam is bad for server resources • Heuristics, blacklisting and CAPTCHAs are used to block spam