If you use the Firefox browser you may want to stop what you are doing right now and upgrade your browser before you are affected by its security flaw if you are using anything less than version 39.0.3.
Mozilla said the attack was “surprisingly developer-focused for an exploit launched a general audience news site,” because it hunted browser and FTP configuration files. It added that the “exploit leaves no trace that it has run on the local machine.”
The organization said the malicious scripts can affect PC and Linux computers, but not Macs. Apple users are still advised to update, though, as hackers could develop a different attack script for OS X. Luckily, the person who spotted the flaw was security researcher Cody Crews, who immediately notified Mozilla. It has patched the flaw with Firefox version 39.0.3, so now would be a good time to get it.