What you need to know about malware

Most common types of malware

It helps to understand how malware works. Some malicious programs will wreak havoc on your computer, while others run quietly in the background. Here are the most common types of malware you're likely to encounter:

• Viruses. Viruses are the most common online threat you'll run into. They are malicious programs that can infect software installed on your computer, delete files and prevent software or operating systems (OS) from running properly.
• Trojan horses. This type can download and install unwanted programs, steal your login credentials, and spread to other computers.
• Rootkit. A rootkit is intended to hide malicious activity on your computer. It may be programs running in the background or malicious activities such as a person remotely gaining access to your files.
• Adware. This is malware that displays unwanted and disruptive ads. Some adware is designed to trick you into paying to make the pop-ups go away.
• Spyware. Spyware can track your activities. Some spyware will simply keep track of which sites you visit, while other kinds monitor what you type and record your login credentials.
• Ransomware. This is a malware category that's particularly malicious since it can lock you out of your files and trick you into paying to regain access.

How malware infects your computer

Malware uses various techniques to infiltrate your OS and files. Understanding how a malware infection happens will help you take precautions.

In many cases, malware infects a computer because a user clicked on a malicious download link. You might inadvertently click on one if you attempt to download movies or video games illegally. And some websites can even offer software downloads that seem legitimate but are bundled with malware.

Another malware technique is to send malicious programs as email attachments that you open. Your computer can also become infected if you accept pop-ups from a malicious site or if you use an unsecured Wi-Fi network. It's also possible to infect a computer by adding malicious code to a legitimate webpage.

Common signs a computer is infected

Some malware infections are easy to notice, but many malicious programs run quietly in the background. Here are some common signs of infection:

• You keep seeing pop-ups with ads or messages that look like technical errors.
• Your antivirus program detected an issue.
• Your computer is slow or crashes, or there's a high amount of hard drive activity even when you aren't using your computer.
• Programs seem to open and close by themselves.
• You notice new software or toolbars installed on your computer.
• There are new files on your computer.
• Your browser seems to redirect you automatically to malicious URLs when you browse the web.
• Your contacts receive phishing emails or suspicious attached files from your email address.
• You notice suspicious activity on one of your online accounts.

What to do if your computer is infected with malware

The best thing to do is take preventative measures to protect your home computer. You should have an antivirus program installed and enable automatic updates for it. Also, use a firewall to prevent malicious programs from connecting to the internet.

Browser extensions can keep you safe online by identifying malicious sites and blocking harmful downloads. Create regular backups of your data, and always ask yourself whether a site, link, or email is safe before clicking on it.

If your computer is infected with malware, try these steps:

• Don't take unnecessary risks, and avoid shopping online or logging into your online accounts.
• Disconnect your computer from the internet to prevent malware from spreading to other devices on your home network.
• Many sites offer malware removal tools, but be aware that many of them aren't legitimate and can result in additional malware being installed.
• Boot up your computer in Safe Mode and run an antivirus scan. Delete the infected files your antivirus software finds.
• Look for unwanted software or toolbars installed on your computer and uninstall them.
• Use the Windows System File Checker to find missing or damaged system files.
• If you can't get rid of malware, use the system recovery options on your OS. You may also have to use a repair disc and data backup to reload your entire OS and files.

You can prevent malware infections by using an antivirus program and always being careful with the links you click on.