EDIT
TO EVERYONE ASKING TO OPEN AN ISSUE ON GITHUB, IT HAS BEEN OPEN SINCE JULY 6: https://github.com/LemmyNet/lemmy/issues/3504
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.
Note, my tools is the only solution that exists (currently) for this in regards to csam
Appreciate your work.
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can you elaborate on what an obfuscation overlay is?
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I don’t think random trolls like that would be be that sophisticated, but in any case we can deal with that once we get to that point.
Not hosting images is a far better solution, and also exists.
What’s the best away for be to disable the pictrs directory? Is there a setting to flip in my instance?
Your contributions to the Lemmy ecosystem are much appreciated 🙏🏼
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Imagine if the image link is shared to other people and you aren’t aware of it. You think that’s acceptable?
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I’m usually pretty relaxed when it comes to disclosure of vulnerabilities but this is the kind of issues where I think it would have been better to privately report the issue to the Lemmy dev and wait ( a long time probably) for it to be fixed before disclosing.
Especially since currently there is multiple people abusing the image hosting feature.
Not a big deal, but sometimes it is actually a better practice to give an opportunity to the dev to fix something before forcing them to do so in a hurry.
Nah. Where’s the drama and FUD in behaving like adults? Much better to make a brand new account and spam moral panic all over the fediverse. /smh
Eh… Better make it public so you don’t have people taking a chance with hosting CSAM!
I’ve mentioned this before to a similar reply. But I’ll say it again: this was already publicly known months ago. People just forgot about it because they didn’t think it was a big deal. Now that they realize CSAM is a real issue, I made this post to remind everyone about it again. Bad actors already know about this and really, it isn’t hard to figure out how this work.
Then why didn’t you contact the devs or opened a bug report on GitHub?
Because there’s already an issue dated July 6: https://github.com/LemmyNet/lemmy/issues/3504
Like I said, people already know about this months ago.
Then why are you here parsing it around like it’s something new.
When did I say it was new? Maybe I’m reminding people about this issue from months ago and that it needs more attention? Maybe I want admins to know about the issue so they can do something about it?
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Thanks for this.
I can’t be the only one getting bored with the 8-hr-old accounts spreading FUD.
If you have a legitimate concern, post it from your proper account. Otherwise it looks like you’re just trolling for Spez. It’s pathetic, really.
You’re not concerned because you’re not an admin. Of course you only bothered to check my account profile and not the actual post. If the issue I stated above doesn’t bother you, then it’s only a matter of time until people start seriously abusing it. Or who knows, somebody already is and we just aren’t aware of it yet.
If you’re not just trolling, what is your main account?
I’m not concerned because people smarter than us have said it isn’t a concern. So long as they preserve their safe harbor shield, instance admins are not generally liable for content posted by users.
Who are these people that are smarter than us? Do you know them? What are their qualifications?
Did you not consider that not everyone is subject to American law and that there are other nations who have different laws? Did you not consider how diverse the Lemmy instances are and most do not fall under American law?
How come that every Lemmy admin who replied to this post expressed their concern regarding this issue? Explain to me why admins like sunasaurus and db0 are working on tools and solutions to address this problem if, according to you, this is not a concern.
Are you REALLY SURE that this is NOT a concern?
Qualified person here. You’re spreading FUD.
The fact that someone can upload illegal content to a lemmy server doesn’t change whether or not it is associated with a post. The two are mutually exclusive issues:
- moderation of user submitted content
- moderation of abuse of hosting functionality (illegal or otherwise)
Both are real issues that need to be addressed, obviously, but it’s simply not the case that a server admin’s only visibility into the content hosted on their server is only that which a user associates with a post. If you know any admins like that, do them a favor and let them know they have no business running a lemmy server.
Did you even read the post?
Yes. Now, assuming you read mine, do you believe the two issues at hand are interrelated, or entirely orthogonal?
Who are these people that are smarter than us? Do you know them? What are their qualifications?
I don’t know and I don’t need to know. They are clearly capable of reading sources that are authoritative (e.g. EFF) and applying a modicum of logic and common sense. Their response is rational rather than breathless and dramatic moral panic.
Did you not consider that not everyone is subject to American law…?
Of course there are countries other than the US. International safe harbor exists for a reason. Can you name one country that doesn’t have a safe harbor provision for web site hosts? Just one.
Did you not consider [that] most [instances] do not fall under American law?
It would be interesting to know how many Lemmy instances don’t fall under US law. I don’t know. Do you? Based on which source?
How come that every Lemmy admin who replied to this post expressed their concern regarding this issue? Explain to me why admins like sunasaurus and db0 are working on tools and solutions to address this problem if, according to you, this is not a concern.
So that’s two who are working on tools. Not panicked and not viewing this as a giant problem. Two out of thousands. It’s an exceptionally low percentage and not even remotely statistically significant.
Are you REALLY SURE that this is NOT a concern?
A concern? Sure. Is anyone going to prison if they don’t bow to your demands right now as you’ve suggested up and down this thread? Unlikely.
What is your usual account? Why are you hiding? Do you plan to plant evidence and then call the authorities?
Again, you are assuming everything is based on American law. What is up with people always thinking that American laws apply everywhere in the world?
“Do you plan to plant evidence and then call the authorities?” No but be very careful about statements like this.
In the end, you admitted that this is a concern anyway. Congrats. Can’t believe it took so much to hammer it into your head.
So you’re just going to ignore any inconvenient points and glom onto my agreement that this issue is a small concern? You think that constitutes “winning”?
TBH, if you need to win an argument with an internet stranger that badly, I’m happy to oblige?
I was going to just let it go, but it’s late and my patience is exhausted.
…be very careful about statements like this.
Or what? You’ll have your dad beat up my dad?
Who are these people that are smarter than us? Do you know them? What are their qualifications?
“Have you poured through the data yourself? The numbers? The figures?”
Additionally this isn’t the community where this needs to be addressed. Either contact the admins or open an issue on GitHub.
Issue has been opened two months ago: https://github.com/LemmyNet/lemmy/issues/3236 https://github.com/LemmyNet/lemmy/issues/3504
In the USA, admins being liable is not really true
Are individuals granted the same 230 protections as organizations when it comes to self-hosting an instance? I doubt people are forming non-profits for their self hosting endeavors
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Thank you! That’s a clear and concise explanation of section 230. I’ve always heard it in reference to big social media companies but your link clearly shows the protections extend to individuals and users as well
Most admins aren’t in the USA. But that’s not really the issue here is it?
https://programming.dev/pictrs/image/9cd1e9f4-ba82-432c-91ce-911db05ccc6e.jpeg testing the linking of a picture that’s never been posted for science.
I can see it. It’s a very nice artwork.
https://sh.itjust.works/pictrs/image/08ff5623-e553-4d00-a6e2-e9fb6798a972.webp
Here is another test ^ I use a different instance to better illustrate the point because it’s easy to upload images in comments. Nobody in shitjustworks will see this picture in their instance so nobody can report this picture.
This picture is just Salvadaor Dali by the way.
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So you’re telling me you’re NOT bothered if CSAM was sitting on your server and shared with others without your knowledge? Do you think all countries have the same laws? You don’t think any of this is an issue?
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You’re not an admin so of course you don’t care. How come every admin in this thread has expressed their concern? Because it IS a concern. :)
To take your analogy, it could be someone hosts a collection of material in your yard and invites all the pedos to use your yard to see and share other material.
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Excellent point. I suspect that there already are Reddit operatives here trying to stir up FUD. In fact, that’s what I think this OP is.
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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.
Or just disable image uploads completely. We got by on Reddit without any built-in image hosting functionality for over a decade, so Lemmy should be fine without it as well - especially considering that we don’t really have many image-heavy communities, besides the NSFW instances. I mean, storage costs money you know, and with Lemmy being run by volunteers, it makes even more sense to get rid of image hosting to save costs.
I don’t have the pictrs container running on my instance.
💯 I really hope this is in the next update
Just being able to paste images in comments (usually screenshots in my case, related to the comment in question) is super convenient. Images are for more than just memes and photos.
This can be easily implemented client-side, like how third-party Reddit clients have been doing for years, by uploading to the likes of Imgur. Shift the responsibility away from the Lemmy server and onto dedicated image hosts, who have the storage to spare, plus manpower/policies to deal with illegal content.
Desktop users exist, third-party hosts have a history of deciding to forbid hotlinking, third-party hosts have a history of suddenly deleting all (e.g. PhotoBucket) or some (e.g. Imgur) images .
If I didn’t have to worry about other people “uploading” (via caching) CSAM to my server, I’d far prefer if it was me who hosts those images.
Desktop users exist
So do Desktop tools like Flameshot, which can directly upload to image hosts and copy the URL to the clipboard which makes it easy to share images, and there also exists third-party Desktop web-clients such as Photon, which could be updated with that functionality as well. But with Lemmy itself being open source, it wouldn’t take much effort to modify the code to use a third-party image host.
have a history of deciding to forbid hotlinking
There are plenty of hosts which do allow hotlinking though, like imgbb.com
history of suddenly deleting all (e.g. PhotoBucket) or some (e.g. Imgur) images .
Not a big loss, IMO. Lemmy isn’t an image hosting nor an image-centric site, it’s a text-heavy forum at first instance, and anyone posting images are encouraged to provide text alts for the benefit of blind users, so images not persisting isn’t a big deal.
If image persistence is really that important, there are other services which are better suited for that, such as Pixelfed. But in the first place, I wouldn’t rely on some random Lemmy server, which is vulnerable to DDoS and other attacks and could go down at any time (also why the importance on decentralization - no single instance is infallible). I mean, when there’s no guarantee that a Lemmy instance will even be there tomorrow, is there really a need to worry about image persistence?
I feel like you are saying “there are other issues, we should not care and forget about it”, it seems very defeatist to me.
catbox exists
Yeah, this is a big issue. I know Lemmy blew up a bit before it was truly ready for prime time but I hope this cleans up.
Yes, an app designed to receive user generated content will allow users to upload arbitrary content. This is not really an issue unique to Lemmy, and can be fixed by banning abusive users
As far as I know, people don’t homebrew Reddit.
Sites like reddit could have about the same problem. You can post to some obscure profile and use reddit as image hosting and it might take quite some time before anyone notices. This is a little worse though because it wouldn’t even be listed on a profile page.
This is specifically about a way of uploading that you as admin won’t know about unless you manually check for it.
Except admins need to go through the database to catch it. Mods can’t catch it. Admins without access to the database or object storage can’t catch it.
Why does Lemmy even ship its own image host? There are plenty of places to upload images you want to post that are already good at hosting images, arguably better than pictrs is for some applications. Running your own opens up whole categories of new problems like this that are inessential to running a federated link aggregator. People selfhost Lemmy and turn around and dump the images for “their” image host in S3 anyway.
We should all get out of the image hosting business unless we really want to be there.
Convenience for end-users and avoiding link rot is probably one of the reasons.
Seems to not be paying off though; having whole communities and instances close is pretty inconvenient.
and avoiding link rot
Lemmy seems built to destroy information, rot links. Unlike Reddit has been for 15 years, when a person deletes their account Lemmy removes all posts and comments, creating a black hole.
Not only are the comments disappeared from the person who deleted their account, all the comments made by other users disappear on those posts and comments.
Right now, a single user just deleting one comment results in the entire branch of comment replies to just disappear.
Installing an instance was done pretty quickly… over 1000 new instances went online in June because of the Reddit API change. But once that instance goes offline, all the communities hosted there are orphaned and no cleanup code really exists to salvage any of it - because the whole system was built around deleting comments and posts - and deleting an instance is pretty much a purging of everything they ever created in the minds of the designers.
Funny, I couldn’t even get pict-rs working on my instance. I don’t need it, either. I just upload to an FTP server when I need to share something.
Good. It’s better that way until the issues are resolved.
seems like the solution to this should be to automatically remove images that haven’t been posted, after like 3 minutes
3 minutes is way too short. You could upload and it be gone by the time you post.
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The idea is good, but 3 minutes is horribly short and would remove in tons of posts with broken images. After one hour would be bad UX but workable. 3 minutes would just suck :D
The 3 minutes would only kick in if an image was uploaded but then never posted. So nobody would see it anyway in any case.
This route would avoid the issue but also help save on space too.
What happens if user spends over 3 minutes to write the post after uploading image?
Would user create a post with broken image link? or would there be some kind of “call home” API call on create post page so image wouldn’t be removed? (which has risk that API call could be replicated by a bot)
Could allow for like one hour of keep-alive pings before it’s deleted and the client is told to notify the user of this
Also: rate limits that gradually increase are good.
That’s exactly what I meant, yeah.
Write the post and then upload the image?
This could be handled by the client. Get the Ruleset for image uploads (max size, format, etc.), Validate the image within the client, only upload when the post is published.
Then the delay between post and image only depends on your internet connection and the user can still take 3 hours to write a post.
That is a good point. Could potentially not upload the image until the post is created instead of at image choosing, which would also alleviate the issue. But I’m not sure how that would work across web and mobile clients.
I think that’s the best solution. I can’t see a reason any client couldn’t upload the image when the post is submitted. Currently the uploader is some fancy javascript deal and it’s unnecessary.
The solution is to base it upon the user session timer.
As in when you’d normally get automatically logged out? If so, I’m not sure that would work since Lemmy uses JWTs that don’t expire (or if they do, not for a very long time) it seems.
Or you set a flag that says something like “incomplete image” and then only once user completes whatever operation by hitting “submit” do you then set it to complete.
And maybe while an image is not yet complete, only the uploading user can view the image.
This is one way to solve it.
Or make it like 1hr and don’t let the user know the url of the uploaded image until they post it, that way it wouldn’t be able to be shared or reported.
It’s difficult to display an image without the client knowing the URL, but it would be possible to use a temporary URL that only works for that signed-in user.
Store the image in memory, or in browser cache.
