Security Sift

Introduction It’s been my observation that when it comes to XSS prevention, angle brackets associated with HTML and script tags (<>) often get the majority of the attention. While eliminating script tags as a potential XSS vector is a great start, just as important, and seemingly most forgotten when it comes to input validation and output encoding, are double (“) and single (‘) quotes. Whether they are completely ignored or…

Here I’ll demonstrate how it’s possible to evade ASP .NET Request Validation and take advantage of Internet Explorer 9 quirks to execute a working XSS exploit.  Let’s look at a scenario… You suspect an ASP.NET application you’re testing is vulnerable to reflected XSS because it displays user input to the screen.  Its login page includes a registration function and if a user inputs the wrong registration number (passed via a…