In the recent times, most of the systems connected to Internet are getting infected with malware and some of these systems are even becoming zombies for the attacker. When user knowingly or unknowingly visits a malware website, his system gets infected. Attackers do this by exploiting vulnerabilities in web browser and it is possible to acquire control over the underlying Operating System. Once attacker compromises the user's web browsers, he can instruct the browser to visit the attacker's website by using number of redirections. During the process, user's web browser downloads the malware without the intervention of the user. Once the malware is downloaded, it would be placed in the file system and responds as per the instructions of the attacker. These types of attacks mostly happen through JavaScript and malicious HTML tags. Browser JSGuard detects and defends from such attacks made through the web browser. It blocks access to the harmful, inappropriate and dangerous websites that may contain malicious content.