Trojan-Downloader:W32/Agent.D is typically found on certain malicious sites. When activated, it downloads an EXE file from a website and saves it into the root directory of the C: drive. The downloaded file is then run.
Depending on the settings of your F-Secure security product, it will either automatically delete, quarantine or rename the suspect file, or ask you for a desired action.
More information on the scanning and removal options available in your F-Secure product can be found in the Help Center.
You may also refer to the Knowledge Base on the F-Secure Community site for more information.
Technically. Agent.D's executable file is an HTML Application (HTA file). This file type is normally run by the MSHTA.EXE application, a program that comes standard with Windows.
While it is running, Agent.Dhides its window from the user when it is running by resizing the window to a zero size and preventing it from being visible in the Taskbar.
The trojan also drops a file named CMD.BAT into the root directory of the C: drive. This BAT file is used for cleanup purposes only: it deletes the trojan's file from the hard disk.