FastSupport are sometimes abused by cyber criminals, commonly through 'tech support' scammers. Users encounter random redirects to deceptive sites claiming that system is damaged and encouraging them to contact tech support using various telephone numbers. After calling, users are asked to grant cyber criminals, who claim to be 'certified technicians', remote access to their systems via FastSupport or another remote computer access service.
These scammers then suggest that the system is infected and ask users to pay for removal of malware that does actually not exist. In some, cases cyber criminals call the victim and claim to be from Microsoft, Apple, or another tech company.
These people then demand remote access to solve technical issues, etc. Bear in mind, that giving remote access to cyber criminals can be very dangerous. While, commonly, they strive to trick you into paying for services that are not required, they can install trojans, key loggers, and other malicious software on your computer.
If you gave access to connect to your computer to a suspicious third party agent, we recommend scanning your computer with a legitimate antivirus program, removing all the found threats, and then changing your passwords for online banking, email, and social media accounts.