For many years ModSecurity was a number one free open source web application firewall for the Apache web server. At this year's BlackHat we would like to announce that right now ModSecurity is also available for IIS and nginx servers, making it a first free cross-platform WAF for on-line services. Using MSRC response process and CVE-2011-3414 as an example, we will show how ModSecurity can be used in early detection of attacks and mitigation of vulnerabilities affecting web infrastructure. We will also show how OWASP ModSecurity Core Rule Set can be used as a base for detection of 0-day attacks on Apache, IIS and nginx servers.