Tech support scammers are actively exploiting a Firefox browser lock (browlock) bug to persuade potential victims to call their fake Windows support line within 5 minutes to avoid having their systems disabled. The bug allows the crooks to lock the targets’ browser, preventing them from closing the browser tab displaying the tech support scam page. This is done by spamming them with a large amount of authorization confirmation prompts because there is no rate limiting to prevent it. Mozilla’s Paul Z..hlcke is currently working on a fix that should be provided with a future Firefox release and block scammers from locking their victims’ web browsers.
Source: https://www.bleepingcomputer.com/news/security/tech-support-scammers-are-abusing-a-new-firefox-browser-lock-bug/