Accepted media type image allows files with .jpg extension to be uploaded even if contents are not an image

[kendrickluong]

Description:

Accepted Media Types filter on file uploads set to image/* incorrectly accepts files that are not images but have .jpg extension

Steps to reproduce:

1. Settings > File Upload > Accepted Media Types: images/*
2. Upload an actual_image.jpg file goes through
3. Upload random.cer file Media Type Not Accepted Application/pkix-cert
4. Rename random.cer to random.jpg file goes through

Expected behavior:

random.jpg should not be uploaded

Server Setup Information:

• Version of Rocket.Chat Server: 1.0.3
• Operating System: RHEL 7.2 (reports as 4.15.0-1035-aws)
• Deployment Method: docker
• Number of Running Instances: 3
• DB Replicaset Oplog:
• NodeJS Version: 8.11.4
• MongoDB Version: 3.6.12

[reetp]

I think the problem is that automatic detection of file types is something less than reliable and can still be fooled. It isn't Rocketchats fault - it's an industry wide issue.

eg https://stackoverflow.com/questions/24662959/use-file-content-to-determine-mime-type-with-node-js

I'd suggest this can closed and added as a NFR here:

https://github.com/RocketChat/feature-requests

but I think it is unlikely to get fixed in hurry.

[Jacko50]

I managed to work around this by installing incron and having a trigger whenever a file is put into the Rocket uploads directory to look for "image" in the output of the command file --mime-type and deleting if false.

[kendrickluong]

I managed to work around this by installing incron and having a trigger whenever a file is put into the Rocket uploads directory to look for "image" in the output of the command file --mime-type and deleting if false.

What's the behaviour of rocketchat if incron delete the file? Does the send/receiver both get broken links?

[github-actions[bot]]

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[4li-ra]

any proggress?

[anoniz]

any progress? did this issue got solved?

[reetp]

any progress? did this issue got solved?

This is a way old issue but I don't think there is an easy solution short of some sort of massive processing either on the client or on the server.

Please note there are a plethora of issues related to file uploads and file types.

This has some interesting comments on mime type detection for instance:

https://github.com/RocketChat/Rocket.Chat/issues/31906