Windows 8.1 Pro: Defender triggers alarm after installing KB4580347

[German]Does the monthly security quality rollup for Windows 8.1 KB4580347 trigger a false alarm for Windows Defender? A German blog reader told me that a few days ago by mail.


German blog reader Manuel K. contacted me by e-mail and described a strange situation with Windows 8.1 Pro. I'll post it here in the blog, maybe there are more people affected. Manuel writes the following:

Defender raises false alarms after installing KB4580347:

I would like to inform you about the following reproducible problem with KB4580347 [I have been working on this problem for more than a month now and have researched in the internet without results]. I deliberately keep it short in order not to take up too much of your time.

Problem description: After installing the 2020-10 – Monthly Security Quality Rollup for Windows 8.1 for x64-based systems (KB 4580347), Windows Defender reports the following error during the manual scan (quick and complete scan)

„The preliminary results of the scan indicate that there may be malicious or potentially unwanted software on the system. You can check the found items after the scan is complete."

However, after the scan, no items are displayed under "History" (neither for "Quarantined items" or "Allowed items", nor for "All detected items").

The message also appears after reinstalling the operating system (after formatting the SSD) and is therefore reproducible [no software and no files other than Windows present; no message before installing KB4580347, only after installation].

The affected Win 8.1 Pro x64 systems are:

AMD Phenom II X4 940, GA-MA770-UD3, 8 GB, Samsung SSD 860 EVO 1TB, NVIDIA GeForce GTX 760
Acer Aspire One 522, AMD-C50, 4 GB, Samsung SSD 840 EVO 250 GB [[I have not checked the error reproduction on this system.]

[Two Intel-based notebooks are not affected.]

I assume a false alarm: Scans with "desinfec't 2020" (Kaspersky, Sophos, F-Secure, ESET, Open Threat Scanner) do not find malware or unwanted software [Archives and mailboxes were also scanned].

The following ambiguities remain: Uninstalling KB4580347 (through "System Restore") does not correct the problem.

The problem occurred on one system already in connection with the September rollup – and only with the October rollup for further investigation.

During a research Manuel found only hints for problems of Windows Security Essentials from 2017 regarding similar error messages. But this is not applicable here. For further investigation Manuel asked for advice, like the location of the log files, which I had also given him. There was also this post with the remark that antivirus software detected a Dell printer driver incorrectly as malware. The case was excluded by the user. Therefore I assume a false alarm based on the above description. Hence the question: Did any of you have similar experiences?

Cookies helps to fund this blog: Cookie settings

This entry was posted in issue, Windows and tagged , . Bookmark the permalink.

Leave a Reply

Your email address will not be published. Required fields are marked *