Microsoft Defender Antivirus review

Microsoft Defender Antivirus is the free baseline every Windows PC already has, and it has a real ransomware layer if you turn it on. In the Windows Security app, the Ransomware protection section lets you configure Controlled folder access, which prevents unknown apps from changing files in protected folders, and set up OneDrive to help you recover from an attack. Microsoft's documentation notes that Controlled folder access is a Windows feature and is not available on macOS or Linux. Defender also provides real-time protection plus quick, full and custom scans with quarantine. The drawbacks are about effort and coverage. Controlled folder access has to be configured before it protects anything, and Windows Security does not add the phishing filters, VPN or family tools of paid suites. The separate Microsoft Defender app with extra features comes with Microsoft 365 Personal at $99.99 per year, which makes sense mainly if you want Office and 1 TB of OneDrive anyway.

Who it is for

Windows users who want a free baseline and are willing to switch on the ransomware settings themselves.

Price

Free in Windows; the Microsoft Defender app comes with Microsoft 365 Personal at $99.99 per year.

Ransomware protection : In this section you can configure Controlled folder access , which prevents unknown apps from changing files in protected folders.
Quoted from the vendor pricing page on November 10, 2026.

Key features

• Controlled folder access stops unknown apps from changing files in protected folders
• OneDrive options to help recover from a ransomware attack
• Real-time virus, malware and ransomware protection
• Quick, full and custom scans with quarantine
• Included with Windows at no extra cost

Strengths and weaknesses

• Strength: Free and already installed on Windows
• Strength: Controlled folder access is a real protected-folder layer
• Strength: Ties into OneDrive file recovery
• Weakness: Controlled folder access is off until you configure it
• Weakness: Windows only for this feature, per Microsoft
• Weakness: No phishing, VPN or extras of a paid suite in Windows Security itself

Key facts

• Ransomware feature: Controlled folder access
• Recovery: OneDrive ransomware recovery options
• Platforms: Windows (feature not on macOS or Linux)
• Price: Free with Windows

Where it ranks

Microsoft Defender Antivirus is No. 9 in our Best Ransomware Protection Software verdict.