A Trojan horse may take control of your computer files by using a program manager that allows a hacker to install, execute, open, or close programs. The hacker can gain remote control of your cursor and keyboard and can even send mass e-mails from your infected computer. It can run in the background, hiding its presence. A Trojan is usually disguised as a harmless software program and may also be distributed as an e-mail attachment. Opening the program or attachment may cause an auto-installation process that loads the downloader onto your computer and download third-party programs on your computer, resulting in the installation of unwanted programs without your knowledge or consent, and jeopardizing your privacy. Trojans can also open a port on your computer that enable a hacker to gain remote control of your computer.