My computer has been remotely accessed – what could have caused this?

Programs like "Trojan horse" types, such as Back Orifice and Netbus, can lead to this issue. Both are Windows 95/98 applications designed to give unauthorized users access to your system (usually with malicious intent) over the Internet.

For someone to use BO on your computer, you must install the server application. This typically happens when you download an app or receive the server EXE via an email and are tricked into running it. This is why it's called a Trojan horse – you must either knowingly or unknowingly run the EXE to install the server. It doesn't spread on its own like a virus (for more on Trojans and viruses, see How Computer Viruses Work). Once you run the server EXE, it installs and starts automatically every time your computer boots up.

After the server is installed, a malicious actor can use the BO client program to take control of your machine remotely, running programs or deleting files... Needless to say, this is not something you want. Thankfully, Back Orifice is easy to detect, either manually or with the right software.

These links will help you learn more: