W32/ERSS.FST!tr is classified as a trojan.
A trojan is a type of malware that performs activites without the user’s knowledge. These activities commonly include establishing remote access connections, capturing keyboard input, collecting system information, downloading/uploading files, dropping other malware into the infected system, performing denial-of-service (DoS) attacks, and running/terminating processes.
The Fortinet Antivirus Analyst Team is constantly updating our descriptions. Please check the FortiGuard Encyclopedia regularly for updates.
- Make sure that your FortiGate/FortiClient system is using the latest AV database.
- Quarantine/delete files that are detected and replace infected files with clean backup copies.