cross-posted from: https://lemmy.dbzer0.com/post/4500908
In the past months, there’s a been a issue in various instances where accounts would start uploading blatant CSAM to popular communities. First of all this traumatizes anyone who gets to see it before the admins get to it, including the admins who have to review to take it down. Second of all, even if the content is a link to an external site, lemmy sill caches the thumbnail and stores it in the local pict-rs, causing headaches for the admins who have to somehow clear that out. Finally, both image posts and problematic thumbnails are federated to other lemmy instances, and then likewise stored in their pict-rs, causing such content to be stored in their image storage.
This has caused multiple instances to take radical measures, from defederating liberaly, to stopping image uploads to even shutting down.
Today I’m happy to announce that I’ve spend multiple days developing a tool you can plug into your instance to stop this at the source: pictrs-safety
Using a new feature from pictr-rs 0.4.3 we can now cause pictrs to call an arbitary endpoint to validate the content of an image before uploading it. pictrs-safety builds that endpoint which uses an asynchronous approach to validate such images.
I had already developed fedi-safety which could be used to regularly go through your image storage and delete all potential CSAM. I have now extended fedi-safety to plug into pict-rs safety and scan images sent by pict-rs.
The end effect is that any images uploaded or federated into your instance will be scanned in advance and if fedi-safety thinks they’re potential CSAM, they will not be uploaded to your image storage at all!
This covers three important vectors for abuse:
- Malicious users cannot upload CSAM to for trolling communities. Even novel GenerativeAI CSAM.
- Users cannot upload CSAM images and never submit a post or comment (making them invisible to admins). The images will be automatically rejected during upload
- Deferated images and thumbnails of CSAM will be rejected by your pict-rs.
Now, that said, this tool is AI-driven and thus, not perfect. There will be false positives, especially around lewd images and images which contain children or child-topics (even if not lewd). This is the bargain we have to take to prevent the bigger problem above.
By my napkin calculations, false positive rates are below 1%, but certainly someone’s innocent meme will eventually be affected. If this happen, I request to just move on as currently we don’t have a way to whitelist specific images. Don’t try to resize or modify the images to pass the filter. It won’t help you.
For lemmy admins:
- pictrs-safety contains a docker-compose sample you can add to your lemmy’s docker-compose. You will need to your put the .env in the same folder, or adjust the provided variables. (All kudos to @[email protected] for the docker support).
- You need to adjust your pict-rs ENVIRONMENT as well. Check the readme.
- fedi-safety must run on a system with GPU. The reason for this is that lemmy provides just a 10-seconds grace period for each upload before it times out the upload regardless of the results. A CPU scan will not be fast enough. However my architecture allows the fedi-safety to run on a different place than pictrs-safety. I am currently running it from my desktop. In fact, if you have a lot of images to scan, you can connect multiple scanning workers to pictrs-safety!
- For those who don’t have access to a GPU, I am working on a NSFW-scanner which will use the AI-Horde directly instead and won’t require using fedi-safety at all. Stay tuned.
For other fediverse software admins
fedi-safety can already be used to scan your image storage for CSAM, so you can also protect yourself and your users, even on mastodon or firefish or whatever.
I will try to provide real-time scanning in the future for each software as well and PRs are welcome.
Divisions by zero
This tool is already active now on divisions by zero. It’s usage should be transparent to you, but do let me know if you notice anything wrong.
Support
If you appreciate the priority work that I’ve put in this tool, please consider supporting this and future development work on liberapay:
All my work is and will always be FOSS and available for all who need it most.
Random Lemmy user makes something that Reddit probably paid thousands and thousands of $ to make.
To be fair there are now off the shelf ai solutions available which were simply impossible 10 or even 5 years ago.
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Be careful with this though. I think I remember some jurisdictions require server owners not to delete CSAM and report it instead. Verify that you aren’t obligated to keep it before deleting it
not upload CSAM to for trolling communities. Even novel GenerativeAI CSAM. Users cannot upload CSAM images and never submit a post or comment (making them invisible to admins). The images will be automatically rejected during upload
There wouldn’t be anything to delete, as it would have never been saved with this.
So the image never touches the server side, even in RAM, it always remains only on the client machine, and it’s checked there?
If so, then this could be a pretty neat tidy way to deal with this issue, otherwise the image is on the server, even if you “delete it real fast” or such, and I imagine then you’d still need to be in compliance with the law regarding saving and reporting it.
Did you read the post? The image is sent to an endpoint that has a hosted AI solution that checks it
It 100% touches the server, it’s just not stored anywhere and gets blocked
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HEY LOCAL PD OFFICE,
SOMEONE TRIED TO UPLOAD SOME POTENTIALLY CHILD PORN TO MY LEMMY INSTANCE.
No… I don’t have an IP for who uploaded it.
Sorry, I don’t know where it came from. It just got federated across the fediverse to me.
No… I don’t have the content either, it doesn’t get saved.
Sorry… I guess I really don’t have any details at all for you.
hosting a lemmy instance in the us is a headache
Hence my reaction to these issues. https://lemmyonline.com/post/459013
But… under new management now, in Germany. https://lemmyonline.com/post/587565
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Does that leave open a possible attack, in which the attacker can just fill up the server’s hard drive with AI-generated CSAM?
Thank you so much for caring, well done!
🫡 Thank you for your service comrade.
You’re a legend db0! FOSS FOREVER!
This is very cool! Too bad I don’t have access to vps with gpu to try it at the moment.
Is it possible to offer this as a service with a small monthly fee (e.g. on demand pricing depending how many images you scan) or donations, so instance owners without gpu can use it?
I’ve love to, but there’s legal concerns about the transfer of potential CSAM to third party services which I’d rather not think about.
As you said this may have to be the bargain of the fediverse. I think a democratic process on the training of said ai might be what gives the best outcomes from this.
I’m curious. How do you train such AI without being raided by the authorities?
You don’t tell them.
disappointed that this uses AI instead of something like Microsoft’s PhotoDNA that compares image hashes. AI has too much (unnecessary & unacceptable) risk of false positives that results in overbroad censorship.
PhotoDNA requires a lot more bureaucratic work than most instance admins can handle, but if you really want it, you can easily plug it into pictrs-safety instead.
However PhotoDNA will not catch novel generativeAI CSAM.
there’s no such thing as “AI-generated CSAM”. CSAM literally is created by abusing a real human child. There’s no such thing as an “AI child”. It would be a much better idea to protect *ACTUAL existing children instead of wasting resources on *checks notes* fiction
You and especially your users won’t know a photorealistic generative AI image is real or not.
Microsoft’s PhotoDNA
My issue with these services is that they aren’t available for non-US people. db0’s project can be deployed anywhere (provided you have a capable GPU).
ok then use Cloudflare’s
That also isn’t available for non-US people.
PhotoDNA is very proprietary…
I don’t see the problem here. What makes you think that the false positives in this case is “unacceptable”? So what if Joe Bloggs isn’t able to share a picture of a random kid (why tho) or an image of a child-like person?
false positives not only leads to unnecessary censorship, but it also wastes resources that would be better used to protect *ACTUAL victims and children (although, the optimal solution is protecting people before any harm is done so that we don’t even need these “band-aid” solutions for reacting afterward)
Fuck Microsoft, always and forever.
Or just turn off image uploads
So I don’t know if I missed something, but I don’t see an explanation of what CSAM is…
Child Sexual Abuse Materials iirc
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