Technology Insights

Double Encoding – One Of The Biggest Enemies While Fixing Cross-Site Scripting (XSS)

“You have X amount of Cross-Site Scripting vulnerabilities”. That is a phrase most web developers have heard at least one time, what is a Cross-Site Scripting vulnerability?

OWASP defines Cross-Site Scripting as:

“Cross-Site Scripting attacks are a type of injection problem, in which malicious scripts are injected into the otherwise benign and trusted web sites. Cross-site scripting (XSS) attacks occur when an attacker uses a web application to send malicious code, generally in the form of a browser side script, to a different end user. Flaws that allow these attacks to succeed are quite widespread and occur anywhere a web application uses input from a user in the output it generates without validating or encoding it.”