https://support.mozilla.org/en-US/kb/push-notifications-firefox https://support.mozilla.org/en-US/kb/push-notifications-firefox#w_how-do-i-revoke-web-push-permissions-for-a-specific-site Are these small popups on bottom right corner? if so then they may just be web push notifications from sites you have allowed to send you notifications. Unfortunately they can sometimes be fake virus or antivirus alerts with McAfee being the common client that is faked. You can revoke permission for these sites in Firefox.