Unable to block uploads from wetransfer.com

SafeSquid Data Loss Prevention module introduced to restrict end users from uploading sensitive or critical information outside the corporate network to prevent data leakage.(Policy Based Upload Control)
India sakshidalvi
Posts: 15
Joined: Thu Jun 03, 2021 9:42 am

Unable to block uploads from wetransfer.com

Post by sakshidalvi » Tue Jun 15, 2021 1:25 pm

The Problem : When I was trying to do checkpoint 5 from basic client scenarios (Upload Control). The task was to block uploading from all the websites except for a list of websites (I gave them Exception category) Following are the policies and profiles I made for the same.
Policies and profiles.png
Policies and profiles.png (37.58 KiB) Viewed 2561 times
DLP policy :
dlp policy.png
dlp policy.png (11.46 KiB) Viewed 2561 times
However after this when I opened images.google.com and tried to upload any image It was blocked by safesquid.
images.google.com blocked.png
images.google.com blocked.png (42 KiB) Viewed 2561 times

India sakshidalvi
Posts: 15
Joined: Thu Jun 03, 2021 9:42 am

Re: Unable to block uploads from wetransfer.com

Post by sakshidalvi » Tue Jun 15, 2021 1:26 pm

When I tried to upload file on wetransfer.com It uploaded successfully eventhough it wasn't in exception category
wetransfer uploading.png
wetransfer uploading.png (251.11 KiB) Viewed 2560 times
Then I checked in the detailed logs and found that images.google.com was using the "file upload" request types. However, wetransfer.com was not using the "file upload" Request type :
images.google has file upload category.png
images.google has file upload category.png (10.83 KiB) Viewed 2560 times
wetransfer did not have file upload category.png
wetransfer did not have file upload category.png (15.8 KiB) Viewed 2560 times

India sakshidalvi
Posts: 15
Joined: Thu Jun 03, 2021 9:42 am

Re: Unable to block uploads from wetransfer.com

Post by sakshidalvi » Tue Jun 15, 2021 1:27 pm

To solve the same I created a custom request type for wetransfer and under content type I used application/json which was seen in the detailed logs.
created custom request type.png
created custom request type.png (15.78 KiB) Viewed 2560 times
My policies and profile after creating custom request type :
policies and profile after custom request type.png
policies and profile after custom request type.png (37.12 KiB) Viewed 2560 times
And after this when I tried uploading on wetransfer.com it didn't go through and I got the following error and when I placed wetransfer.com in EXCEPTION category I was able to upload file.
after custom request wetransfer upload got bloked.png
after custom request wetransfer upload got bloked.png (157.75 KiB) Viewed 2560 times
I just wanted to ask you if this is the correct way to solve the problem?

India aashish97
Posts: 117
Joined: Sat Jul 06, 2019 10:45 am

Re: Unable to block uploads from wetransfer.com

Post by aashish97 » Wed Jun 16, 2021 4:36 am

Hello Sakshi,

There is a lot of flaws in finding the Root Cause of the Problem...
If you look closely not all images.google.com will have File Upload as `Request Type` Added
i.e Not all Request to any website will be having File Upload

Secondly, why did you add Content-Type: application/json as wetranfer.
How did you come to the conclusion that adding that will help?

By going with the current policy a lot other web application will not work regardless whether File Upload is happening or not.

India sakshidalvi
Posts: 15
Joined: Thu Jun 03, 2021 9:42 am

Re: Unable to block uploads from wetransfer.com

Post by sakshidalvi » Wed Jun 16, 2021 10:23 am

I found in detail logs that wetransfer.com was using Content-Type : application/json when I uploaded any file to it.
To limit the request type to only wetransfer.com I added wetransfer.com to the host of the request type so that other web application using the application/json will not get blocked.

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