How to protect your PC with built-in Windows security features

Summary

This guide helps you troubleshoot and resolve: How to protect your PC with built-in Windows security features. Follow the steps below to fix the issue.

Common Causes

Windows includes a suite of built‑in security tools that, when correctly configured, provide strong protection against viruses, ransomware, phishing sites and other online threats. This guide shows small business and home‑office users how to enable and fine‑tune Microsoft Defender, the Windows Firewall and SmartScreen on Windows 10 and Windows 11.

Before You Begin: Ensure Windows Update Is Enabled

Keeping Windows up to date is a foundational security step. Security patches and definition updates are delivered through Windows Update, so confirm it is active before configuring other protections.

1. Press Win + I to open Settings.
2. Select Windows Update from the left‑hand menu.
3. Click Check for updates.
4. Install any available updates and restart your computer if prompted.
5. Ensure Receive updates for other Microsoft products is turned on under Advanced options.

Quick Fix Steps

Turn on real‑time protection in Microsoft Defender

1. Press Win + I to open Settings.
2. Select Privacy & security > Windows Security.
3. Click Open Windows Security.
4. Choose Virus & threat protection.
5. Under Real‑time protection, toggle the switch to On.

Enable the Windows Firewall

1. In the same Windows Security window, select Firewall & network protection.
2. For each relevant network profile (Private and Public), click the profile name and set Microsoft Defender Firewall to On.
3. Note: The Domain profile applies only to computers joined to an Active Directory domain. Standalone small business and home‑office computers typically use the Private or Public profile.

SmartScreen and Browser Protection

1. Microsoft Edge: Open Edge, click the three‑dot menu … > Settings > Privacy, search, and services. Scroll to the Security section and ensure Microsoft Defender SmartScreen is toggled On.
2. Google Chrome: Open Chrome, go to Settings > Privacy and security > Security. Under Safe Browsing, select Enhanced protection.
3. Mozilla Firefox: Open Firefox, go to Settings > Privacy & Security. Scroll to Security and ensure Block dangerous and deceptive content is checked.

Detailed Instructions

Microsoft Defender Antivirus

• Automatic sample submission: In Virus & threat protection settings, turn Automatic sample submission on to help Microsoft improve detection.
• Cloud‑based protection: Ensure Cloud‑delivered protection is enabled for faster, AI‑driven threat analysis.
• Exclusions: Add trusted folders or applications under Exclusions only if they cause false positives.

Ransomware Protection: Controlled Folder Access

Controlled Folder Access helps protect your important files from ransomware by preventing unauthorised applications from making changes to protected folders.

1. Open Windows Security.
2. Select Virus & threat protection.
3. Under Ransomware protection, click Manage ransomware protection.
4. Toggle Controlled folder access to On.
5. Click Protected folders to view or add folders that should be monitored.
6. Click Allow an app through Controlled folder access if a legitimate program is blocked from accessing a protected folder.

Windows Firewall Advanced Configuration

1. Open the Start menu, type Windows Defender Firewall with Advanced Security, and select the result.
2. In the left pane, choose Inbound Rules to view existing rules.
3. To create a new rule, click New Rule… in the right‑hand Actions pane.
4. Select the rule type (e.g., Port), click Next, and specify the protocol and port number.
5. Choose Allow the connection (or Block the connection if you want to restrict traffic).
6. Apply the rule to the appropriate profiles (Private, Public, and Domain if applicable) and give the rule a descriptive name.

Schedule Regular Scans

1. In Windows Security, go to Virus & threat protection.
2. Under Current threats, click Scan options.
3. Select Full scan and click Scan now to perform a comprehensive check.
4. To automate scans: The recommended method for non‑technical users is to use the Windows Security interface for regular quick scans and run a manual full scan monthly. If you prefer Task Scheduler, open Task Scheduler, create a basic task, and set the program to the full path of MpCmdRun.exe (typically located under C:\ProgramData\Microsoft\Windows Defender\Platform\4.18.xxxx.x\MpCmdRun.exe, where the version number varies by build) with the argument -Scan -ScanType 2. Remember to enter the program path and arguments in their respective fields in Task Scheduler.

Troubleshooting

Microsoft Defender Won’t Turn On

• Check for third‑party antivirus software. If another product is installed, Microsoft Defender may be disabled automatically. Uninstall or disable the other solution, then retry.
• Open services.msc and verify that the Microsoft Defender Antivirus Service is set to Automatic (Delayed Start) and is running.
• Open Windows Security > Virus & threat protection > Quick scan. If an error appears, note the error code and search Microsoft’s support site.

Firewall Blocks Legitimate Application

1. When a pop‑up appears stating the app was blocked, click Allow access and select the appropriate network profile.
2. If no prompt appears, open Windows Defender Firewall with Advanced Security and create an inbound/outbound rule for the application’s executable path (e.g., C:\Program Files\AppFolder\App.exe).
3. Ensure the rule is enabled and placed above any conflicting block rules.

SmartScreen Still Allows Suspicious Sites

• Confirm that SmartScreen or Safe Browsing is enabled in the browser settings as described above.
• Clear the browser cache and cookies; corrupted cache data can sometimes bypass protection warnings.
• Update the browser to the latest version – protection relies on up‑to‑date threat definitions.

System Performance Degrades After Enabling Real‑time Protection

1. Open Task Manager (Ctrl + Shift + Esc) and locate the MsMpEng.exe process.
2. If CPU usage consistently exceeds 30 % for more than a few minutes, run a full scan to ensure the system is not infected.
3. Consider adding low‑risk folders (e.g., large media libraries) to Exclusions under Virus & threat protection settings. Use exclusions sparingly.

Still Having Issues?