Blocking file uploads to all sites, unless safelisted

Copper Contributor

We're trying to verify if we can block file uploads through the browser to all sites, unless these sites are part of an approved list or the user has an exception. We currently have a similar solution through a different vendor, but wanted to see if Defender for Endpoint is an alternative.

So, if someone creates a new site, this site would not be allowed to be uploaded to unless the domain is added to an approved list. The alternative would be to block if the file has a specific label. 



29 Replies
Thanks. Looking forward to your response.

@miller34mike, it WORKED. It finally WORKED. Thanks a mill for your help. Screenshot 2023-06-07 at 23.40.36.png



Happy to hear it is working for you! Glad I could help. Just finished building the policy too, will still give it a test. Thanks for running through all of this with me!


Btw, if you block Chrome or Firefox from handling sensitive data (endpoint DLP settings) the Microsoft Purview Extension will override that block BUT specific blocks like this should still work. 

I have create DLP policy with following condition but its seems not working with



sorry to hear you’re having issues with this DLP policy. 

Have you completed the prerequisites for the device that you’re testing this policy with? There a few different onboarding steps that need to be completed. You can confirm these are done using the blog linked below. 

If the prerequisites are met and you’re still having issues then we will do a couple of different tests to narrow down the issue.


yes i have complete all settings. but policies are working partially. and taking too long to sync on system.

Like its blocking for one side but not for the other one. same with copy paste. it is blocking on one machine but not on another machine  



How did you solve this issue? I'm having the exact same problem, exact same policy made and for some reason blocking the file upload isn't working. 



@Brandon_Tuck Its not resolved like still files are getting uploaded on few site i.e chatgpt and other

which websites did the file blocking work? i tried dropbox and it did not work
I am also having this issue. I completed all the prerequisites, would you mind taking a look at the policy I made?