Long story short, the new security update for Raspbian PIXEL is here to patch a security issue that could have been exploited by hackers to invisibly take control of Raspberry Pi devices and cause massive Internet blackouts like the one reported by numerous media outlets at the end of October. Therefore, SSH (Secure Shell) has been disabled by default, making it extremely hard to hijack a Raspberry Pi SBC. However, you should not panic, your Raspberry Pi device is not being hacked, and Raspberry Pi Foundation has no knowledge of them being used in botnets or taken over in large numbers. However, it’s still good practice to protect yourself and prevent such attacks by disabling SSH right now using the Raspberry Pi Configuration (raspi-config) application.