Archives / 2008
  • Using the new rules configuration in UrlScan v3.0 Beta (Part 2)

    I will spend some time dissecting the SQL injection rule posted in the walkthrough for UrlScan. Before I do so, I want to re-iterate the fact that SQL injection is a web application issue, and hence the right place to fix it is in the web application. Sometimes when you are the victim of a SQL storm, it is less than ideal to go figure out all the places your web application might be susceptible. That's where UrlScan comes in and offers a stop gap solution till you can fix the apps, without taking any downtime hit on your site. The one issue here is that of false positives ... and these are hard to predict because different web applications have different requirements and semantics. Nonetheless, UrlScan can offer substantial protection in the face of a SQL Storm at the cost of a some false positives that will cause valid requests to be rejected.

  • UrlScan v3.0 filtering based on Request Entity

    While some folks are rejoicing, others are noticing the lack of scanning for the request entity. Why would we do that? The easy answer is that this is just not possible with an ISAPI filter. In IIS 5 and earlier, there is no API that would allow us to filter request entity, so request entity will never happen there.  In IIS 6, the APIs exist to do this via * script maps, but the performance would be pretty bad.  Also, there is no mechanism to treat the request as a stream, so there would be potential memory utilization problems. So we left it at that and said "can't do it, sorry".

  • Using the new rules configuration in UrlScan v3.0 Beta (Part 1)

    If you haven't noticed already, UrlScan v3.0 Beta is out and it is the answer to all your prayers. Well maybe not all, but it still is nifty. UrlScan 2.5 is widely used and is quite popular. There were a few minor issues with it that were all fixed for UrlScan 3.0. But besides those UrlScan now has the ability to filter based on query strings as well and a new rules syntax lets you specify powerful rules and lets you stay organized while you are at it.

  • Using IPv6 with IIS7

    Besides the US government and certain Asian countries, IPv6 has not really caught on yet, especially here in the US. So how does IIS7 stack up as far as IPv6 support is concerned? Let's walk through the IIS7 feature set to evaluate this. For comparison against IIS 6 you can check out the TechNet article here.

  • SQL Injection Demo

    SQL injection seems to have faded from prominence lately and has become just a buzz word. To make things a little more real I put together a quick demo for it, to demonstrate that you don't necessarily have to go out of your way to make your web application exploitable.

  • Filtering SQL injection from Classic ASP

    SQL injection may be over a decade old, but even the best of us need a reminder once in a while. You should always validate input to your applications! There isn’t a ‘one size fits all’ solution to sanitizing input, so I will attempt to show what a general solution might look like for classic ASP (using VBScript). Remember, you need to keep in mind the specifics of your web application and add/remove things in the sample accordingly. So even though I am focusing on SQL injection here, input validation needs to be done to even prevent cross-site scripting attacks, among others. Check this article on how to prevent XSS to give you an idea of other sorts of validation that would need to be done on user input to secure a web application. If you are looking for something for ASP.NET check out this post from Stefan on the ASP.NET team.