A remote access Trojan or Remote Administrative Tool (RAT) is a malware program that includes a
back door for administrative control over the target computer. RATs are usually downloaded invisibly with a user-requested program -- such as a .exe -- or sent as an email attachment. Once the host system is compromised, the intruder may use it to distribute RATs to other vulnerable computers and establish a
botnet.
Because a RAT enables administrative control, it makes it possible for the intruder to do just about anything on the targeted computer, including:
- Monitoring user behavior through keyloggers or other spyware.
- Accessing confidential information, such as credit card and social security numbers.
- Activating a system's webcam and recording video.
- Taking screenshots.
- Distributing viruses and other malware.
- Formatting drives.
- Deleting, downloading or altering files and file systems.