Keeping information safe

Think of the marks of your class. Confidentiality means that only the teacher and the pupil can see a mark. Integrity means that nobody changes a mark by mistake or on purpose. Availability means that the marks can be opened on the day the teacher needs them. These three aims are the target of information security, and a threat is anything that harms one of them. Unauthorised access, using a computer or an account without permission, harms confidentiality. A program that changes files harms integrity. A computer that stops working harms availability. Many threats come as malware. A virus attaches itself to a file and needs a person to run that file. A worm spreads by itself over a network. A Trojan horse looks useful but hides harm inside. Spyware collects information secretly, and a keylogger records the keys you press. Adware shows unwanted advertisements; it is not a virus. Ransomware locks files and asks for money. Four habits protect you against most of them: install updates, use security software, keep backup copies, and do not open files or links you did not expect. If something looks wrong, stop and tell a trusted adult.