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For most home PCs, leave Microsoft Defender Antivirus real-time protection, security intelligence updates, tamper protection, and Microsoft Defender Firewall on. Also review reputation-based protection and potentially unwanted app blocking. Check Device security for Secure Boot and memory integrity, and consider Controlled folder access if you are prepared to review app blocks. Some options depend on Windows version, device hardware, firmware, or drivers; no single setting protects against every threat.

Start with antivirus protection and updates

Open Windows Security > Virus & threat protection and review its settings. Keep real-time protection enabled, allow security intelligence updates, and leave tamper protection on. Microsoft says Windows obtains security intelligence through Windows Update and provides a manual check for updates. Tamper protection helps prevent apps from changing important security settings silently; an administrator can still change settings in Windows Security while it is enabled. See Microsoft’s Virus and Threat Protection guidance.

Avoid broad antivirus exclusions: excluded files and locations receive less scanning coverage, and routine use does not require them. If you have installed another antivirus product, first check which protection is active; Windows Security may show or defer to that product.

Keep Microsoft Defender Firewall on

In Windows Security > Firewall & network protection, check that the firewall is on for each network profile you use. A private profile is for a network you trust; treat public networks as untrusted. The firewall filters network traffic, and Microsoft warns that turning it off can make a device more vulnerable to unauthorized access.

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If a needed app is blocked, investigate its rule or allow a narrowly scoped exception rather than disabling the firewall. A work-managed PC may enforce settings that you cannot change. See Microsoft’s Firewall and network protection guidance.

Screen apps and downloads

Open Windows Security > App & browser control > Reputation-based protection and review the options shown on your PC. Turn on potentially unwanted app blocking for apps and downloads where available. SmartScreen can help screen for phishing, malware, and potentially unwanted apps. The available controls and defaults vary by Windows version, so use the labels on your device as your guide.

Windows 11 users may also see Smart App Control, which checks apps before they run. It is not a Windows 10 setting, and it cannot necessarily be switched on whenever you choose: availability depends on the device’s state and eligibility. Check its displayed status and Microsoft’s Smart App Control FAQ rather than assuming every Windows 11 PC can enable it.

Consider Controlled folder access for ransomware protection

Controlled folder access can block untrusted apps from changing files in protected folders. It is an additional barrier, not a substitute for backups, and it can interrupt legitimate apps that need to modify protected files.

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  1. Open Windows Security > Virus & threat protection.
  2. Under ransomware protection, select Manage ransomware protection.
  3. Turn on Controlled folder access if the option is available.
  4. If a trusted app is blocked, verify that it is the genuine app before allowing it. Add only the necessary app; an allowed app can access protected files.

Microsoft explains the feature and its app exceptions in its Controlled folder access documentation. Maintain a recoverable backup too: Microsoft describes OneDrive as one option for restoring important files after ransomware. See Microsoft’s virus and threat protection guidance.

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Check Device security without changing firmware blindly

Open Windows Security > Device security and check the status of Secure Boot and core isolation, including memory integrity if shown. These protections depend on hardware and firmware support; memory integrity can also be affected by driver compatibility. Windows may indicate that a capability is unavailable or needs attention. If firmware changes are required, consult the device maker’s instructions rather than changing BIOS or UEFI settings without understanding their effect. Microsoft’s Device security overview explains the capabilities shown in the app.

What to prioritize

Setting Protection layer Practical priority
Defender Antivirus, security intelligence updates, and tamper protection Malware detection and protection-setting integrity Keep on; confirm which antivirus is active if you installed another product.
Microsoft Defender Firewall Unwanted network traffic Keep on for profiles in use; troubleshoot app rules instead of turning it off.
Reputation-based protection and PUA blocking Unsafe apps and downloads Review and enable the available options.
Controlled folder access Unauthorized changes to protected files Optional; use if you can handle legitimate-app blocks and review exceptions carefully.
Secure Boot and memory integrity Device startup and system integrity Check their status; availability depends on the PC’s hardware, firmware, and drivers.
Smart App Control App execution checks Windows 11 only; check whether your device is eligible and what status it displays.
Recoverable backup File recovery if prevention fails Keep a backup separate from the PC’s protective settings; OneDrive is one option documented by Microsoft.

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