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 Windows Defender, the Windows Firewall and SmartScreen on Windows 10 and Windows 11.

Quick Fix Steps

Turn on real‑time protection in Windows 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 network profile (Domain, Private, Public), click the profile name and set Microsoft Defender Firewall to On.

Activate SmartScreen for Microsoft Edge

1. Open Microsoft Edge.
2. Click the three‑dot menu … > Settings > Privacy, search, and services.
3. Scroll to the Security section and ensure Microsoft Defender SmartScreen is toggled On.

Detailed Instructions

Windows Defender (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.

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 (Domain, Private, Public) and give the rule a descriptive name.

SmartScreen Settings for Different Browsers

• Microsoft Edge: As described in the Quick Fix steps, ensure Microsoft Defender SmartScreen is on.
• Google Chrome (if installed):
  1. Open Settings > Privacy and security > Security.
  2. Under Safe Browsing, select Enhanced protection for the highest level of phishing and malware blocking.
• Mozilla Firefox:
  1. Open Options > Privacy & Security.
  2. Scroll to Security and ensure Block dangerous and deceptive content is checked.

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, open Task Scheduler (type it in the Start menu), create a basic task that runs MpCmdRun.exe -Scan -ScanType 2 weekly.

Troubleshooting

Windows Defender Won’t Turn On

• Check for third‑party antivirus software. If another product is installed, Windows Defender may be disabled automatically. Uninstall or disable the other solution, then retry.
• Open services.msc and verify that the Windows Defender Antivirus Service is set to Automatic (Delayed Start) and is running.
• Run 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 is enabled in the browser settings as described above.
• Clear the browser cache and cookies; corrupted cache data can sometimes bypass SmartScreen warnings.
• Update the browser to the latest version – SmartScreen 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?