Stop whatever you’re doing right NOW and update you browser (If your using Firefox that is..)
A bug in Firefox allows it to an ad on an unnamed Russian news site to search and upload files your computer to a server in Ukraine without leaving a trace on your computer. Windows and Linux users are effected by this but, it is also a good idea to Mac users to update to the latest version of Firefox 39.0.3 or Firefox ESR (Extended Support Release) 38.1.1.
“The vulnerability comes from the interaction of the mechanism that enforces JavaScript context separation (the “same origin policy”) and Firefox’s PDF Viewer,” Veditz wrote. “Mozilla products that don’t contain the PDF Viewer, such as Firefox for Android, are not vulnerable.”
He also said users who are using adblockers are unaffected but should also update.
If you don’t know how to update then you can find the instructions here.
