Troj/Agent-FD is a Trojan for the Windows platform.
When Troj/Agent-FD is installed the following files are created:
<Windows system folder>\Filesys.ini
<Windows system folder>\ntfilesys.ini
<Windows system folder>\winupdate.exe
The following registry entry is changed to run winupdate.exe on startup:
HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
Shell
Explorer.exe winupdate.exe
(the default value for this registry entry is "Explorer.exe" which causes the Microsoft file <Windows folder>\Explorer.exe to be run on startup).
The Trojan monitors this registry entry and restores it to the above setting if it is changed.