Prevent malware infection

Malware authors are always looking for new ways to infect computers. Follow the simple tips below to stay protected and minimize threats to your data and accounts.

Keep software up-to-date

Exploits typically use vulnerabilities in popular software such as web browsers, Java, Adobe Flash Player, and Microsoft Office to infect devices. Software updates patch vulnerabilities so they aren't available to exploits anymore.

To keep Microsoft software up to date, ensure that automatic Microsoft Updates are enabled. Also, upgrade to the latest version of Windows to benefit from a host of built-in security enhancements.

Email and other messaging tools are a few of the most common ways your device can get infected. Attachments or links in messages can open malware directly or can stealthily trigger a download. Some emails will give instructions to allow macros or other executable content designed to make it easier for malware to infect your devices.

  • Use an email service that provides protection against malicious attachments, links, and abusive senders. Microsoft Office 365 has built-in antimalware, link protection, and spam filtering.

For more information, see phishing.

Watch out for malicious or compromised websites

By visiting malicious or compromised sites, your device can get infected with malware automatically or you can get tricked into downloading and installing malware. See exploits and exploit kits as an example of how some of these sites can automatically install malware to visiting computers.

To identify potentially harmful websites, keep the following in mind:

  • The initial part (domain) of a website address should represent the company that owns the site you are visiting. Check the domain for misspellings. For example, malicious sites commonly use domain names that swap the letter O with a zero (0) or the letters L and I with a one (1). If example.com is spelled examp1e.com, the site you are visiting is suspect.

  • Sites that aggressively open popups and display misleading buttons often trick users into accepting content through constant popups or mislabeled buttons.

To block malicious websites, use a modern web browser like Microsoft Edge which identifies phishing and malware websites and checks downloads for malware.

If you encounter an unsafe site, click More […] > Send feedback on Microsoft Edge. You can also report unsafe sites directly to Microsoft.

Pirated material on compromised websites

Using pirated content is not only illegal, it can also expose your device to malware. Sites that offer pirated software and media are also often used to distribute malware when the site is visited. Sometimes pirated software is bundled with malware and other unwanted software when downloaded, including intrusive browser plugins and adware.

Users do not openly discuss visits to these sites, so any untoward experience are more likely to stay unreported.

To stay safe, download movies, music, and apps from official publisher websites or stores. Consider running a streamlined OS such as Windows 10 Pro SKU S Mode, which ensures that only vetted apps from the Windows Store are installed.

Don't attach unfamiliar removable drives

Some types of malware can spread by copying themselves to USB flash drives or other removable drives. There are malicious individuals that intentionally prepare and distribute infected drives—leaving these drives in public places to victimize unsuspecting individuals.

Only use removable drives that you are familiar with or that come from a trusted source. If a drive has been used in publicly accessible devices, like computers in a café or a library, make sure you have antimalware running on your computer before you use the drive. Avoid opening unfamiliar files you find on suspect drives, including Office and PDF documents and executable files.

Use a non-administrator account

At the time they are launched, whether inadvertently by a user or automatically, most malware run under the same privileges as the active user. This means that by limiting account privileges, you can prevent malware from making consequential changes any devices.

By default, Windows uses User Account Control (UAC) to provide automatic, granular control of privileges—it temporarily restricts privileges and prompts the active user every time an application attempts to make potentially consequential changes to the system. Although UAC helps limit the privileges of admin users, users can simply override this restriction when prompted. As a result, it is quite easy for an admin user to inadvertently allow malware to run.

To help ensure that everyday activities do not result in malware infection and other potentially catastrophic changes, it is recommended that you use a non-administrator account for regular use. By using a non-administrator account, you can prevent installation of unauthorized apps and prevent inadvertent changes to system settings. Avoid browsing the web or checking email using an account with administrator privileges.

Whenever necessary, log in as an administrator to install apps or make configuration changes that require admin privileges.

Read about creating user accounts and giving administrator privileges

Other safety tips

To further ensure that data is protected from malware as well as other threats:

  • Backup files. Follow the 3-2-1 rule: make 3 copies, store in at least 2 locations, with at least 1 offline copy. Use OneDrive for reliable cloud-based copies that allows access to files from multiple devices and helps recover damaged or lost files, including files locked by ransomware.

  • Be wary when connecting to public hotspots, particularly those that do not require authentication.

  • Use strong passwords and enable multi-factor authentication.

  • Do not use untrusted devices to log on to email, social media, and corporate accounts.

Software solutions

Microsoft provides comprehensive security capabilities that help protect against threats. We recommend:

  • Automatic Microsoft updates keeps software up-to-date to get the latest protections.

  • Controlled folder access stops ransomware in its tracks by preventing unauthorized access to your important files. Controlled folder access locks down folders, allowing only authorized apps to access files. Unauthorized apps, including ransomware and other malicious executable files, DLLs, and scripts are denied access.

  • Microsoft Edge browser protects against threats such as ransomware by preventing exploit kits from running. By using Microsoft SmartScreen, Microsoft Edge blocks access to malicious websites.

  • Microsoft Exchange Online Protection (EOP) offers enterprise-class reliability and protection against spam and malware, while maintaining access to email during and after emergencies.

  • Microsoft Safety Scanner helps remove malicious software from computers. NOTE: This tool does not replace your antimalware product.

  • Microsoft 365 includes Office 365, Windows 10, and Enterprise Mobility + Security. These resources power productivity while providing intelligent security across users, devices, and data.

  • Office 365 Advanced Threat Protection includes machine learning capabilities that block dangerous emails, including millions of emails carrying ransomware downloaders.

  • OneDrive for Business can back up files, which you would then use to restore files in the event of an infection.

  • Microsoft Defender Advanced Threat Protection provides comprehensive endpoint protection, detection, and response capabilities to help prevent ransomware. In the event of a breach, Microsoft Defender ATP alerts security operations teams about suspicious activities and automatically attempts to resolve the problem. This includes alerts for suspicious PowerShell commands, connecting to a TOR website, launching self-replicated copies, and deletion of volume shadow copies. Try Microsoft Defender ATP free of charge.

  • Windows Hello for Business replaces passwords with strong two-factor authentication on your devices. This authentication consists of a new type of user credential that is tied to a device and uses a biometric or PIN. It lets user authenticate to an Active Directory or Azure Active Directory account.

  • Microsoft Security Essentials provides real-time protection for your home or small business device that guards against viruses, spyware, and other malicious software.

What to do with a malware infection

Microsoft Defender ATP antivirus capabilities helps reduce the chances of infection and will automatically remove threats that it detects.

In case threat removal is unsuccessful, read about troubleshooting malware detection and removal problems.