These days, the biggest threat to an organization's network security comes from its public Web site and the Web-based applications found there. Unlike internal-only network services such as databases-which can be sealed off from the outside via firewalls-a public Web site is generally accessible to anyone who wants to view it, making application security an issue. As networks have become more secure, vulnerabilities in Web applications have inevitably attracted the attention of hackers, both criminal and recreational, who have devised techniques to exploit these holes. In fact, attacks upon the Web application layer now exceed those conducted at the network level, and can have consequences which are just as damaging.

Some enlightened software architects and developers are becoming educated on these threats to application security and are designing their Web-based applications with security in mind. By "baking in" application security from the start of the development process, rather than trying to "brush it on" at the end, you are much more likely to create secure applications that will withstand hackers' attacks. However, even the most meticulous and security-aware C# or VB.NET code can still be vulnerable to attack if you neglect to secure the Web.config configuration files of your application. Incorrectly configured Web-based applications can be just as dangerous as those that have been incorrectly coded. To make matters worse, many configuration settings actually default to insecure values.

This article lists five of the "worst offenders" of misconfigurations of application security that are universally problematic for all ASP.NET Web-based applications. Part two of this article will list an additional five misconfigurations that are specifically applicable to ASP.NET sites that use Web Forms authentication. So without further ado, let's get started!