Fundamentals of cyber security - AQAMalicious code

Malicious code is software written to harm or cause issues with a computer. This is also referred to as malware and comes in a number of different forms. In all its forms, the code has been written to either harm or steal data from your computer system.

There are a number of types of malware, which include:

• viruses
• trojans
• ransomware
• spyware
• adware

Viruses

A virus is a piece of malware that infects a computer, and then replicates itself to be passed onto another computer.

Anti-virus software holds a large database of known viruses. If a program that is installing, or file that is being opened, appears to be similar to one of these, the anti-virus software will warn the user and, depending on the type of anti-virus, place all related files into a secure folder until it is confirmed that it is safe.

Trojans

A Trojan appears to be a piece of harmless software, often given away for free, that contains malicious code hidden inside. This only appears once the gifted software is installed. It was named after the Greek myth of the Trojan horse.

Ransomware

Ransomware hijacks the data on a computer system by encrypting it and demanding that the owners pay money for it to be decrypted.

Having up-to-date anti-virus software and educating users to not open suspicious attachments will help protect from ransomware.

Spyware

Spyware is a type of malware that collects the activity on a computer system and sends the data it collects to another person without the owner being aware.

If a computer has been infected by spyware, it could be sending back everything that is typed, or the sites that are visited, or even where the user is clicking on their screen. Spyware that records what is being typed is known as a keylogger. Keyloggers attempt to find out usernames and passwords by collecting everything that is entered into the system, which allows the hacker to search for personal data.

Most anti-virus software will also look for spyware in the same way as viruses. Specialist anti-spyware software is also available.

Adware

Adware is software that either causes pop-ups or windows that will not close. Generally, the pop-ups or windows display advertisements. Many anti-virus programs will detect and prevent adware infecting a computer system, but specialist anti-adware programs also exist.