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).
As problem states, "The SELECT permission was denied on the object 'Address', database 'CNET_85731', schema 'dbo' ".
I wonder you can quite simply solve this way:
- Open SQL Server Management studio
- Navigate to the database 'CNET_85731' >> Security >> Users
- Right click on the one which you are using in your code
- And finally, just select 'db_datareader' inside "Database Role membership" section.
Now, I hope you should not get this error again.
Best Answer
There should be some db roles related to the membership tables, eg aspnet_profile_fullaccess. Make sure the account you're using is a member of the appropriate role.
You should NOT assign the user you connect to the DB as dbowner privilege. The account should have only the rights it needs & nothing more. If you grant dbo & someone were to exploit a flaw in your website they would have full uncontrolled access to your entire db to what they wanted - delete tables, change data at will.