My nextcloud has Illegal Software from Microsoft Defender

my nextcloud has been blocked by my organization so I ask them why it is blocked and they told me that Microsoft has blocked it with the reason containing “Illegal software”.
I would like to specify that I don’t have pirated software on my NextCloud but I have legal software ISOs that I keep there as a backup.
My problem is how Microsoft Defener figured this out.
I shared with a colleague the installation of a software that he cannot download from the original site, could this be it?
Or do you give full access to Defender even without a user?

Best Regards

Maybe a false positive. Do you have a hash e.g. MD5 or SHA256 from the file? Do not post it here. Search it on the internet.

That is a problem of your organization resp. your personal problem, if synchronized files become blocked. - See your organization’s security policy.
It oalso may depend on the content of the ISO files. For example an ISO of the Ultimate Boot CD becomes blocked by Windows Defender, due to its content - even the ISO is oldr, than 10 years…

Only, if your Nextcloud Desktop client becomes blocked itself by Defender (and does not start), it might be caused by Nextcloud.

Wait, is your nextcloud server administered by your organization OR is your nextcloud server run at your home? Do you use the desktop client or access the file through the browser when at the organization? Please give us details

Dear All,
I use the web browser on my private computer to connect to my nextcloud. My company uses o365 with OneDrive.
I’m sure the file is correct but I can’t say the same for all the other files.
I only shared this file with a colleague who uses the company computer.
I looked on Microsoft to see if I could see or ask anything, but only the corporate user with the correct account can talk to Microsoft and I don’t have that.

I have removed all the files that could have problems and the existing share now I can only wait and hope.


For such software, it is for them difficult to know if you have the licence or not (and for the users of the company you shared content with, it would perhaps be illegal to use this software). But did you share this ISO?


How is a software illegal when it is not installed?



Well, that colleague probably downloaded it onto a company computer where it was scanned by Windows Defender, causing your organisation to block the download location of the file, which in this case was your Nextcloud.

The question is, what exactly do they mean by “illegal”? I don’t think they mean that your Nextcloud is distributing pirated files, but rather that it’s against your organisation’s policy to download random ISOs or executables from the internet, which is probably why your colleague couldn’t download the file from its original source in the first place.