Parrot TDS (Traffic Direction System) has infected various web servers hosting more than 16,500 websites, ranging from adult content sites, personal websites, university sites, and local government sites.
The situation discovered by Avast and is currently being used to run a campaign called FakeUpdate that distributes the NetSupport Remote Access Trojan (RAT) via fake browser update notifications.
Parrot TDS acts as a gateway for further malicious campaigns to reach potential victims. Attackers buy TDS services to filter incoming traffic and send it to the final destination serving malicious content.
A detailed technical analysis shared by Avast here.