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Microsoft Defender SmartScreen

FeatureWindows 8.1, 10, 11
Checked against official documentationLast reviewed 1 min read

Microsoft Defender SmartScreen is a Windows security feature that checks downloaded apps and visited websites against Microsoft's reputation data. For files that few people have downloaded yet, it shows the blue 'Windows protected your PC' screen, even when the file is signed and clean.

1How reputation works

SmartScreen judges files by reputation: how many people downloaded and ran them and whether problems were reported. A new program, or a new version, starts with little reputation, so warnings are common in its first weeks even with a valid code signature.

2Before you click 'Run anyway'

Download only from the publisher's official site. Check the digital signature (file Properties > Digital Signatures) and compare the SHA-256 hash with the one the publisher lists, for example with Get-FileHash <file> -Algorithm SHA256 in PowerShell.

If the publisher is unknown, the signature is missing or the hash differs, do not run the file.

3Settings

SmartScreen is controlled in Windows Security > App & browser control > Reputation-based protection. Keeping it on is recommended.

How to check a download that SmartScreen warns about

  1. Right-click the file > Properties > Digital Signatures and check the signer name.
  2. Open PowerShell and run: Get-FileHash <path-to-file> -Algorithm SHA256
  3. Compare the hash with the one on the publisher's official page.
  4. Only if both match, select 'More info' > 'Run anyway' on the SmartScreen screen.

Cautions

  • Do not turn SmartScreen off to install one program.
  • A signature proves who published a file, not that every version is free of bugs.

Sources

  1. Microsoft Defender SmartScreen (Microsoft Learn) learn.microsoft.com

Note: Rain Cleaner publishes its SHA-256 hashes and signature details on its Trust Center page.

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