Firefox: NoScript plug-in

Is seems like no browser is safe from security exploits these days, not even Firefox. Although, there's an extension that allows you to make the Firefox browser more secure, it's called 'No Script'.

The No Script extension works by preemptively blocking JavaScript, Java and other potentially dangerous content from untrusted sites that could contain malicious scripts. The biggest problem using this extension is training it, but once you do it works really well.