An IIS application pool

I think you are attacking it from the wrong angle by trying to encode all posted data.

Note that a "<" could also come from other outside sources, like a database field, a configuration, a file, a feed and so on.

Furthermore, "<" is not inherently dangerous. It's only dangerous in a specific context: when writing strings that haven't been encoded to HTML output (because of XSS).

In other contexts different sub-strings are dangerous, for example, if you write an user-provided URL into a link, the sub-string "javascript:" may be dangerous. The single quote character on the other hand is dangerous when interpolating strings in SQL queries, but perfectly safe if it is a part of a name submitted from a form or read from a database field.

The bottom line is: you can't filter random input for dangerous characters, because any character may be dangerous under the right circumstances. You should encode at the point where some specific characters may become dangerous because they cross into a different sub-language where they have special meaning. When you write a string to HTML, you should encode characters that have special meaning in HTML, using Server.HtmlEncode. If you pass a string to a dynamic SQL statement, you should encode different characters (or better, let the framework do it for you by using prepared statements or the like)..

When you are sure you HTML-encode everywhere you pass strings to HTML, then set ValidateRequest="false" in the <%@ Page ... %> directive in your .aspx file(s).

In .NET 4 you may need to do a little more. Sometimes it's necessary to also add <httpRuntime requestValidationMode="2.0" /> to web.config (reference).

The article you liked in the other post actually did a really good job of this.

Immediate Recycle

• Web.config changes
• Machine.config changes
• Global.asax changes
• Bin directory changes
• App_Code changes

Delayed Recycle

Can occur with multiple changes in other locations, typically, I've only noticed this with changes to .aspx or .cs/.vb files though. Adding temporary text, csv or other files has not resulted in issues for me.

NOTE: These are all app-domain recycles, and not actual recycles of the pool. Typically the application POOL will only recycle based on settings in IIS (Number of requests, memory limit, idle time, or scheduled restart).