MSIL/Agent.OIS!tr.dldr is classified as a downloader trojan.
A downloader trojan is a type of malware that has the capability to download other malicious files or an updated version of itself.
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.