Firefox doesn't contain any malware when downloaded directly from Mozilla (as is the case when automatically updating). Either Firefox was downloaded from a third-party site, or malicious software was installed and it infected Firefox. In any case, see the following article for a list of anti-malware tools to get rid of the infection. * [[Troubleshoot Firefox issues caused by malware]] If the problem persists, refer to a forum that specializes in malware removal. * https://forums.malwarebytes.org/index.php?showtopic=9573 * http://malwaretips.com/Forum-Malware-Removal-Assistance