Chapter 11: Protecting E-Mail

Overview

Most e-mail is bogus or malicious. For several years now, spam has accounted for over 60% of all e-mail. That means more bogus e-mail is being sent than legitimate messages. And the percentage only increased even more after the United States CAN-SPAM Act was enacted on January 1, 2004. Most worm outbreaks in the last five years were delivered inside the corporate firewall via e-mail. E-mail value-added service provider MessageLabs (www.messagelabs.com) shows that on average, viruses and worms appeared in one of every 30 e-mails sent on the Internet in 2004 and 2005. During a popular worm outbreak, that figure routinely averaged one out of five e-mails for weeks at a time.

Malicious phishing e-mails remain a huge problem. Users are sent bogus e-mails posing as legitimate entities to trick users into revealing financial information. The Anti-Phishing Working Group (www.antiphishing.org) reported over 5,000 distinct phishing web sites in August 2005, largely driven by e-mail directed traffic. This is despite the fact that most companies routinely scan for malware at Internet and e-mail server access points, deploy antivirus software to the desktop, and run anti-spam software. Clearly, e-mail is a popular hacker target and needs to be a top priority in any computer defense plan. This chapter discusses the most common e-mail threats and how to protect against them.