1. Victor Ivanov

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