EDIT
TO EVERYONE ASKING TO OPEN AN ISSUE ON GITHUB, IT HAS BEEN OPEN SINCE JULY 6: https://github.com/LemmyNet/lemmy/issues/3504
June 24 - https://github.com/LemmyNet/lemmy/issues/3236
TO EVERYONE SAYING THAT THIS IS NOT A CONCERN: Everybody has different laws in their countries (in other words, not everyone is American), and whether or not an admin is liable for such content residing in their servers without their knowledge, don't you think it's still an issue anyway? Are you not bothered by the fact that somebody could be sharing illegal images from your server without you ever knowing? Is that okay with you? OR are you only saying this because you're NOT an admin? Different admins have already responded in the comments and have suggested ways to solve the problem because they are genuinely concerned about this problem as much as I am. Thank you to all the hard working admins. I appreciate and love you all.
ORIGINAL POST
cross-posted from: https://lemmy.ca/post/4273025
You can upload images to a Lemmy instance without anyone knowing that the image is there if the admins are not regularly checking their pictrs database.
To do this, you create a post on any Lemmy instance, upload an image, and never click the "Create" button. The post is never created but the image is uploaded. Because the post isn't created, nobody knows that the image is uploaded.
You can also go to any post, upload a picture in the comment, copy the URL and never post the comment. You can also upload an image as your avatar or banner and just close the tab. The image will still reside in the server.
You can (possibly) do the same with community icons and banners.
Why does this matter?
Because anyone can upload illegal images without the admin knowing and the admin will be liable for it. With everything that has been going on lately, I wanted to remind all of you about this. Don't think that disabling cache is enough. Bad actors can secretly stash illegal images on your Lemmy instance if you aren't checking!
These bad actors can then share these links around and you would never know! They can report it to the FBI and if you haven't taken it down (because you did not know) for a certain period, say goodbye to your instance and see you in court.
Only your backend admins who have access to the database (or object storage or whatever) can check this, meaning non-backend admins and moderators WILL NOT BE ABLE TO MONITOR THESE, and regular users WILL NOT BE ABLE TO REPORT THESE.
Aren't these images deleted if they aren't used for the post/comment/banner/avatar/icon?
NOPE! The image actually stays uploaded! Lemmy doesn't check if the images are used! Try it out yourself. Just make sure to copy the link by copying the link text or copying it by clicking the image then "copy image link".
How come this hasn't been addressed before?
I don't know. I am fairly certain that this has been brought up before. Nobody paid attention but I'm bringing it up again after all the shit that happened in the past week. I can't even find it on the GitHub issue tracker.
I'm an instance administrator, what the fuck do I do?
Check your pictrs images (good luck) or nuke it. Disable pictrs, restrict sign ups, or watch your database like a hawk. You can also delete your instance.
Good luck.
Just my two cents, but I feel it's quite irresponsible to post a "how to exploit this platform" guide ON the platform.
This has been known forever. Any bad actor already knows about this. There's no reason to hide this. I am reminding people so solutions can be solved sooner. I will keep reminding until the problem is solved.
Yeah, it's been acknowledged and solutions have been discussed as future Todos
https://github.com/LemmyNet/lemmy/pull/1809#discussion_r889164824
https://github.com/LemmyNet/lemmy/issues/3504
I imagine it should be prioritized though, along with some of the other malicious upload issue mitigation bugs.
Thank you. I did not see this one but it's almost two months old now. This is what I was talking about when I said that it was already a known issue back then. it just isn't being addressed. I hope this post will give more attention to this problem.
Meh. I main 4chan. All sorts of shit get uploaded on 4chan, yet it still exists. I'm not saying nothing should be done, but no need to panic. Quietly delete the images periodically. In terms of what users can do, I suggest a report system where after a certain number of similar reports, the media gets auto pulled for moderation.
"Quietly delete the images periodically". If only it was made easier for admins. You can't even report these images because nobody knows it was there in the first place.