The other day I was troubleshooting 100%  CPU utilization on a SQL Server 2008 database server. The server had 100 or so databases of varying sizes however none were larger than a few hundred MB and each database had a corresponding web site on a separate web server.  Since the server hosted quite a few databases the high CPU needed to be resolved quickly because it was causing issues for everyone.  High CPU on a database server can often be symptomatic of a issues occurring outside the server. In this case the real issue was in fact being caused by a SQL Injection attack on a web server.

Source : Solving SQL Server High CPU with IIS Request Filtering | Peter Viola

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Another one of the great built-in features of IIS 8 is Dynamic IP Restrictions (DIPR). With a few simple configuration steps you can quickly set limits for blocking IP addresses based on the number of concurrent requests or frequency of requests over a period time. With these parameters in place IIS will take over blocking requests unattended thereby making your server more secure.

Source : Preventing Automated Attacks with IIS Dynamic IP Restrictions | Peter Viola

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