Drive-by downloads planted on legitimate sites (e.g., via "structural" and other vulnerabilities in web applications) cause web sites to get blacklisted by Google, Yahoo, and other search engines and browsers. In this talk, I describe the technical architecture and implementation of mod_antimalware, a novel, open-source containment technology for web servers that can be used to 1) quarantine web-based malware infections before they impact users, 2) allow web pages to safely be served even while a site is infected, and 3) give webmasters time to recover from an attack before their web sites get blacklisted by popular search engines and browsers.