This type of trojan secretly downloads malicious files from a remote server, then installs and executes the files.
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.
This trojan-downloader is distributed as a file attachment to spam e-mails. The attached programs are typically labelled using legitimate-sounding document names, such as 'invoice', as a simple form of social engineering.
On execution of the attached file, the trojan-downloader will attempt to install itself onto the machine, then contact a remote server for additional files and/or instructions.