Includes securing your server, protecting confidential documents on your site, safe CGI programming, client security, and privacy. http://www.w3.org/Security/Faq/
This site is designed to help user to learn about what kinds of security risks exist and how to prevent them from happening. http://www.cgisecurity.com/
Full text of a paper discussing an 'attack' that threatens both privacy and data integrity. Written by Edward W. Felten, Dirk Balfanz, Drew Dean, and Dan S. Wallach. Available in various formats including PDF and Postscript. http://www.cs.princeton.edu/sip/WebSpoofing/