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Microsoft Defender has one key weakness its rivals don’t

Nothing beats free antivirus protection on Windows, like Microsoft Defender, but some of that software might not be as strong as you think based on a new study from an anti-malware assessment company.

The latest AV-Comparatives report shows data that reveals Microsoft Defender doesn’t perform as well with virus scans when it is offline when compared to competitors.

In the study, spotted by Neowin, AV-Comparatives performed two specific tests. The first is file detection and the second is malware protection. File detection had both an offline and online mode, and the latter option doesn’t. With file detection, the group tested how well antivirus software can detect good files versus malicious files. With malware protection, meanwhile, it is all about preventing a malicious program from making changes.

In the file detection tests, Microsoft Defender ranked poorly when tested in offline mode. It had a 60.3% detection rate compared to others on the list like Avast’s 94.2%, or Kasperksy’s 78%. Only Trend Micro ranked worse than Microsoft on offline detection, coming in at 36.1% detection. In the online mode, though, Microsoft Defender netted a 98.8% detection rate, up at the top with Avast’s 99.5%.

AV Comparatives Test Results chart.

This is something that is intended by design, as cloud-based antivirus services check your PC against the latest threats. Yet, there are faults, too, as not every PC is always online to get the latest signatures and protections from Microsoft or other antivirus companies.

“The test gives an indication of how cloud-dependent each product is, and consequently how well it protects the system when an internet connection is not available. We would suggest that vendors of highly cloud-dependent products should warn users appropriately,” notes AV-Comparatives.

Looking at the protection rates, Microsoft still didn’t do too bad in testing where 10,040 malware samples were injected into systems. NortonLifeLock had a 100% protection rate with no compromised files, and Microsoft had a 99.95% protection rate, with 4 compromised files. Yet, false positives need to be accounted for in the number, with Microsoft getting 5, and Norton, 4.

AV-Comparatives protection rate graph.

For all that data, at the end of the AV-Comparatives report, the group still ends up giving Microsoft a win. Microsoft Defender got the Advanced “+” award, along with other players like Avast, AVG, Avira, Kaspersky, McAfee, and NortonLifeLock. One small fault doesn’t make an antivirus fatal, but you still might want to be careful with which files you open when your PC is offline, as you never know when a virus might strike and when antivirus software might not be at its most effective.

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