A Back Door is a means of access to a computer program. A Back Door circumvents security mechanisms such as firewalls and network & host IDS. Sometimes, programmers install a Back Door in order to access the program for troubleshooting or other purposes. Hackers often detect and exploit Back Doors in order to install malicious software on a user's computer. In some cases, a worm is designed to take advantage of a Back Door created by an earlier attack. Whether installed as an administrative tool or a means of attack, a Back Door is a security risk, because if one exists, hackers will find it and use it for malicious purposes. There are three kinds of Back Doors: Active Back Doors originate outbound connections to one or more hosts. Passive Back Doors listen on one or more ports for incoming connections from one or more hosts. Attack-based Back Doors are the "unknown back doors." These generally arise from a buffer-overflow exploit of poorly-written programs, and result in command-level access to the compromised system. |