Malware is the term used to refer to any type of code or program that is used for a malicious purpose. Cybercriminals use malware for many different reasons but common types of malware are used for stealing your confidential information, holding your computer to ransom or installing other programs without your knowledge. Use this guidance to learn about malware and how to protect yourself. Tip: You can protect yourself from malware by using anti-virus software and safe behaviour online. Protect yourself from malware Take the following steps to significantly reduce your risk of being affected by malware: Use anti-virus software and automatically download signature updates daily. Learn about anti-virus software. Keep all your other software up to date too. Learn about updating sofware. Use strong passwords and passphrases. Learn how to create – and remember – strong passwords. Backup your files regularly – ideally every day. Learn about how to back up files. Disable Microsoft Office macros. (Macros are small programs used to automate simple tasks in Microsoft Office documents but can be used maliciously – visit the Microsoft website for information on disabling macros in your version of Office). Use safe behaviour online. Learn about how to use email safely and browse the web safely. Stay informed on the latest threats – sign up for the ACSC's Alert Service. Regularly check the software installed on your computer, tablet and other devices and uninstall any programs or software that is unused. If you see new programs or software that you did not agree to install, search the program name or ask your local computer repairer or retailer about the program, to see whether it is safe to use. Prevent malware by installing applications safely Malware is distributed in several ways: By spam email or messages (either as a link or an attachment) By malicious websites that attempt to install the malware when you visit, by exploiting weaknesses in your software By masquerading as a good application you download and install yourself. Some malware even pretends to be anti-virus or security products. Protect yourself by only installing the files you need and sourcing them from well known and legitimate app stores. Don’t download applications from third-party download sites. Don’t click on online ads to download applications and do use ad-blocking software. Don’t download and install applications from peer to peer networks – you never know who has changed the files. Don’t click on links in emails or instant messages, or execute attachments unless you are sure they are legitimate. Use a spam filter to protect yourself from malicious messages. Don’t install applications received from contacts, say via email or USB sticks, without scanning them with your anti-virus application first. Learn more about malware There are many different types of malware but most are used to either steal your information, your computer’s resources or your money. This table lists some of the most common types of malware affecting people and businesses in the wild today. Type What it does Trojans and backdoors Traditionally trojans were programs that appear to serve a useful purpose but do something malicious when run. Trojans may steal information, download additional malicious files or even provide a ‘backdoor’ into your computer for a hacker – allowing them to do almost anything they like. Ransomware Malware that makes your computer or files unusable until you pay a fee. Essentially extortion by malware. Keyloggers Logs every keystroke you make and then sends that information, including passwords, bank account numbers, and credit card numbers, to scammers for fraudulent use. Viruses and Worms Viruses are malicious programs that infect files, inserting themselves into the file’s code and then running whenever the file is used. Worms are standalone malicious programs that spread themselves from computer to computer. Similar to trojans, viruses and worms can have many different payloads – for example, they can steal your information, download and install other malicious files, delete your files or even send spam. The following signs may indicate there is malware on your computer: your web browser starts on a different homepage than normal your files are inaccessible random error messages appear, or new programs, toolbars and icons have been installed. To check if your computer is infected run a full scan using your anti-virus software and follow the instructions to remove it. Read the UK NCSC guide on mitigating malware Stay ahead of the latest cyber threats. Sign up for the ACSC's Alert Service, a free service to inform you of the latest cyber threats and how to manage them.