What is malicious code?

Malicious code is unwanted files or programs that can cause harm to a computer or compromise data stored on a computer. Various classifications of malicious code include viruses, worms, and Trojan horses.

How can you protect yourself from malicious code?

• Install and maintain antivirus software. Antivirus software recognizes malware and protects your computer against it. Installing antivirus software from a reputable vendor is an important step in preventing and detecting infections. Always visit vendor sites directly rather than clicking on advertisements or email links. Because attackers are continually creating new viruses and other forms of malicious code, it is important to keep your antivirus software up-to-date.
• Use caution with links and attachments.Take appropriate precautions when using email and web browsers to reduce the risk of an infection. Be wary of unsolicited email attachments and use caution when clicking on email links, even if they seem to come from people you know.
• Block pop-up advertisements.Pop-up blockers disable windows that could potentially contain malicious code. Most browsers have a free feature that can be enabled to block pop-up advertisements.
• Use an account with limited permissions. When navigating the web, it's a good security practice to use an account with limited permissions. If you do become infected, restricted permissions keep the malicious code from spreading and escalating to an administrative account.
• Disable external media AutoRun and AutoPlay features. Disabling AutoRun and AutoPlay features prevents external media infected with malicious code from automatically running on your computer.
• Change your passwords. If you believe your computer is infected, change your passwords. This includes any passwords for websites that may have been cached in your web browser. Create and use strong passwords, making them difficult for attackers to guess.
• Keep software updated. Install software patches on your computer so attackers do not take advantage of known vulnerabilities. Consider enabling automatic updates, when available.
• Back up data. Regularly back up your documents, photos, and important email messages to the cloud or to an external hard drive. In the event of an infection, your information will not be lost.
• Install or enable a firewall. Firewalls can prevent some types of infection by blocking malicious traffic before it enters your computer. Some operating systems include a firewall; if the operating system you are using includes one, enable it.
• Use anti-spyware tools. Spyware is a common virus source, but you can minimize infections by using a program that identifies and removes spyware. Most antivirus software includes an anti-spyware option; ensure you enable it.
• Monitor accounts. Look for any unauthorized use of, or unusual activity on, your accounts—especially banking accounts. If you identify unauthorized or unusual activity, contact your account provider immediately.
• Avoid using public Wi-Fi. Unsecured public Wi-Fi may allow an attacker to intercept your device’s network traffic and gain access to your personal information.

Malware (short for 'malicious software') is software that cybercriminals use to harm your computer system or network. Cybercriminals can use malware to gain access to your computer without you knowing, in targeted or broad-based attacks.

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