A trojan, or trojan horse, is a seemingly legitimate program which secretly performs other, usually malicious, functions. It is usually user-initiated and does not replicate.
Trojan:W32/Agent.FL is a Visual Basic file that attempts to connect to a remote sites, presumably for further activity. The file also drops another file onto the Windows root folder of the affected system.
At time of writing, the server Agent.FL connects to was inactive.
Execution
On execution, Agent.FL will connect to pages from one of the following domains: