Is worrying about XSS,CSRF,sql injection, cookie stealing enough to cover web-security?

Question

Web applications on uncompromised computers are vulnerable to XSS,CRSF,sql injection attacks and cookie stealing in unsecure wifi environments.

To prevent those security

Answer 1

The easy answer is "No you're not invulnerable - nobody is!"

This is a good start, but there are a few other things you could do. The main one you haven't mentioned is validation of untrusted data against a white-list and this is important as it spans multiple exploits such as both SQLi and XSS. Take a look at OWASP Top 10 for .NET developers part 1: Injection and in particular, the section about "All input must be validated against a whitelist of acceptable value ranges".

Next up, you should apply the principle of least privilege to the accounts connecting to your SQL Server. See the heading under this name in the previous link.

Given you're working with ASP.NET, make sure Request Validation remains on and if you absolutely, positively need to disable it, just do it at a page level. More on this in Request Validation, DotNetNuke and design utopia.

For your output encoding, the main thing is to ensure that you're encoding for the right context. HTML encoding != JavaScript encoding != CSS encoding. More on this in OWASP Top 10 for .NET developers part 2: Cross-Site Scripting (XSS).

For the cookies, make them HTTP only and if possible, only allow them to be served securely (if you're happy to only run over HTTPS). Try putting your web.config through the web.config security analyser which will help point you in the right direction.

Another CSRF defense - albeit one with a usability impact - is CAPTCHA. Obviously you want to use this sparingly but if you've got any really critical functions you want to protect, this puts a pretty swift stop to it. More in OWASP Top 10 for .NET developers part 5: Cross-Site Request Forgery (CSRF).

Other than that, it sounds like you're aware of many of the important principles. It won't make you invulnerable, but it's a good start.