Windows Defender took action against malicious software: Here’s what you need to know

By: Madeleine Dean
2 minute read

Since mid-February, many Windows 10 users have encountered a strange Windows Defender message, informing them that the antivirus took action against malicious software. The only problem is that after a thorough search, no malware appears on the list. The results in the Windows Defender’s history confirm that the scan did not detect anything, but the notification shown in the action center suggests that the antivirus took action against malicious software.

As a result, users are left in the unknown as to what malicious software has been detected. Also, the fact that this message occurs daily makes many users wonder whether Windows Defender works properly or not.

Here’s how one user describes this ambiguous Windows Defender message:

I scan using windows defender and get a message “WD scanned your computer … and took action against malicious software”.
Good, my computer is now clean, right? Apparently not, because when I scan again, I get the same result.

So, to see what the problem is, I check “history” in WD, looking at quarantined items and deleted items – but nothing shows, so it seems that no action was in fact taken. So, is my computer clean or not? And what has WD actually done?

What we know about this mysterious message

This ambiguous message appears both after a full and a quick scan. After using an additional anti-malware tool to perform a system scan, users report that Windows Defender continues to display the same intriguing message.

Most likely this is a bug in Windows Defender itself. The issue could be just a glitch in Defender’s notifications feature after a recent update.

However, many users believe this message is triggered by malware that Defender is not able to completely remove from the system. The malware re-installs itself upon the next boot. This may not be a far-fetched hypothesis because right after boot up, when users run a quick scan with Defender, they get the message indicating that the tool took action against malicious software. When they run the scan again, Windows Defender doesn’t find any threats.

However, if users restart their computers and follow the same steps, they get the same results. The initial scan indicates that Defender found and took action against malicious software, but then the second scan indicates no threats have been found.

All’s well that ends well

The good news is that apparently Microsoft has recently solved this problem. Many users confirm they haven’t encountered this error message since the beginning of March. Try installing the latest Windows Defender updates on your computer, and the annoying “Windows Defender took action against malicious software” message should be history.

RELATED STORIES YOU NEED TO CHECK OUT:

For various PC problems, we recommend this tool.

This software will repair common computer errors, protect you from file loss, malware, hardware failure and optimize your PC for maximum performance. Fix PC issues now in 3 easy steps:

  1. Download this PC Repair Tool rated "Excellent" on TrustPilot.com.
  2. Click “Start Scan” to find Windows issues that could be causing PC problems.
  3. Click “Repair All” to fix all issues with Patended Technologies (requires upgrade).

Discussions

Next up

Best Windows 10 antivirus software to use in 2018

By: Radu Tyrsina
7 minute read

Update – 2018 will soon come to an end and we already have a guide on what is the best antivirus you should get in […]

Continue Reading

These features are out for good with Windows 10 version 1809

iamsovy@gmail.com' By: Sovan Mandal
2 minute read

Microsoft is all set to launch its next big update, Windows 10 version 1809 in October. While that should be a nice piece of news […]

Continue Reading

Windows 10 18H2 builds no longer receive new features

By: Matthew Adams
3 minute read

The Windows 10 October 2018 Update (otherwise 18H2) rollout might now be two to three weeks away. For the last few months, new build previews […]

Continue Reading