The FBI and the U.S. Cybersecurity and Infrastructure Security Agency are urging users of popular email services like Gmail and Outlook to be on the lookout for a dangerous and potentially costly ransomware scheme. A bulletin released this week detailed a warning for the Medusa ransomware gang, a group that’s been active since 2021.

The FBI, MS-ISAC and CISA released a joint cybersecurity advisory about the Medusa ransomware variant, advising people and organizations to use multifactor authentication and other strategies to prevent attacks from the ransomware-as-a-service provider that has targeted hundreds since 2021.

Medusa demands a ransom payment of thousands alongside a threat of releasing embarrassing information to the public.