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:

https://liberapay.com/db0/

All my work is and will always be FOSS and available for all who need it most.

  • space_comrade [he/him]@hexbear.netEnglish
    1·
    10 months ago

    Couldn’t this be more efficiently solved by having only approved users post images? Like people with some posts/comments and positive karma (or whatever it’s called on lemmy).

    • dyma@lemmy.worldEnglish
      1·
      10 months ago

      it’s my understanding that the csam datasets (once already labeled by people) are hashed to the point of being unrecognizable before being passed around.

      • DaPorkchop_@lemmy.ml
        0·
        10 months ago

        I don’t think training a model on hashes would be particularly useful - if the model were able to get any meaningful information out of it, that would mean the hash function itself is somehow leaking enough of the original contents to determine the image contents (which would essentially mean the hash function is broken beyond all repair)

    • Awoo [she/her]@hexbear.netEnglish
      2·
      10 months ago

      For abuse detection, you need to use a service that has been vetted by an actual lawyer.

      Lmao because every tech company out there is toooootallly doing that lmao. Come onnnnn give me a break, you’re on the programming.dev instance and you’re saying this shit? Have you ever shipped anything ever? You’re calling for something above and beyond anything that actually happens in reality.

      The weirdest part of what you’re demanding is that your demand makes fediverse LESS protected. Imperfectly implemented protection is better than NO protection and yet you think people are safer legally by implementing nothing at all? You’re out of your fucking mind.

        • Awoo [she/her]@hexbear.netEnglish
          1·
          10 months ago

          Drop the ad hominem attacks and argue the point smuglord

          Just say “insult” ffs. Speak like a normal human being. This isn’t a debate and you win absolutely nothing by using debatebro reddit language.

          Nobody has to argue with your stupid ass making absurd demands on an account with 10 whole comments in its entire history. It’s incredibly obvious wrecker behaviour.

          • xXthrowawayXx [none/use name]@hexbear.netEnglish
            1·
            10 months ago

            Lay off. This person is right.

            We here at hexbear are concerned about protecting people from seeing csam. That’s good. The rest of lemmy is concerned about that and the very real consequences of csam uploads for the sites, which is getting dropped by hosting and registrar and prosecuted for distributing.

            There are already cases where that kind of legal dos attack has worked, there’s even cases of anti csam organizations uploading it to reverse image search sites and then serving them papers when the reverse image search site displays the uploaded image to compare with nonexistent results.

            The person you’re replying to isn’t trying to fuck shit up, they’re telling you that this tool won’t actually solve the problem it’s marketed for.

            E: edited for clarity and kindness

    • ChunkMcHorkle@lemmy.dbzer0.com
      0·
      10 months ago

      For abuse detection, you need to use a service that has been vetted by an actual lawyer.

      Name one. That exists and already works on Fediverse instances.

        • ChunkMcHorkle@lemmy.dbzer0.com
          1·
          10 months ago

          That’s not how this works.

          So you can’t name one either.

          If you’re running an instance, it’s your responsibility to find an appropriate tool.

          That’s exactly what the admin here did, and what’s more, he did so because he was forced to do so by a lack of “appropriate” or even adequate tools.

          Hence the straightforward question you failed to answer.

          I don’t run an instance. CSAM is but one of the many reasons why. But I have been paying attention to the discussions regarding the flood of it here, and the impossibilities involved in starting from scratch with preventing/blocking this on a federated instance.

          But for reasons I cannot begin to fathom, and with an intense interest in seeing this anti-CSAM tool remain unused, you are blithely sailing by all that with a demand for using a tool you personally could not even name and obviously does not exist in acceptable form, or it would already have been gladly implemented.

          Glad he’s ignoring you and carrying on. I think I’ll do the same.

    • gamer@lemm.ee
      0·
      10 months ago

      Are you a lawyer? This feels like FUD.

      I strongly advise anyone against using this software in production, as you will be on the hook for anything this software doesn’t catch.

      So if you don’t use this software, you’re not on the hook for the pictures that this tool doesn’t catch?

        • gamer@lemm.ee
          1·
          10 months ago

          I think you’re confused by the purpose of that statement. When the authors say not to use it for anything important, they’re basically trying to waive liability (informally). It’s kind of like how every open source license has a statement like:

          THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED …

          If you use an open source project for air traffic control software, and a bug causes a bunch of people to die, that’s your fault, not the author of the software. The CLIP people are essentially saying that you shouldn’t use their software to build something that requires a lot of accuracy since it probably wasn’t designed to be as accurate as you need it to be.

          But what I’m wondering is why you’re being so dramatic about this. You’re claiming that it’s highly dangerous/reckless/risky to use it, yet hand waving over the why.

    • Vqhm@lemmy.world
      01·
      10 months ago

      On Reddit there were always so many concern Karen’s peddling FUD when you say anything critical of pedos. For the longest time on Reddit all you had to do was see if the user also posted in pedofriends.

      It was so obvious.

      Any attempt to do anything that might impact a pedophile and there was quickly a brigade saying why that was a wrong.

      No. Any action that supports pedophiles is morally wrong and we should NOT let perfect be the enemy of good when trying to make it more difficult to be a pedophile or support pedophiles.

      If you have a solution that’s better, implement it and share it as Open Source.

      Otherwise crawl back in your pedo hole at reddit and leave us alone.

        • Vqhm@lemmy.world
          01·
          10 months ago

          I called concern troll and then mentioned that on Reddit the subreddit pedofriends uses concern trolling as a tactic to prevent people from doing anything about pedophiles.

          I never said you were a pedophile, but way to out yourself as overly concerned with people being labeled pedos cuz you have such a big heart for protecting pedophiles.

      • Gabu@lemmy.world
        0·
        10 months ago

        While the OP’s concerns were largely… dubious(?), simply going through with literally whatever solution is just as big of a problem. I haven’t reviewed anything about this implementation in depth, thus can’t make any statements towards quality or truthfulness (except that 1% FP seems very optimistic), but you shouldn’t simply assume it will solve your problem without introducing another. Having said that, the author appears very well intentioned and has experience on the subject, so the veredict shouldn’t take long.

        • Vqhm@lemmy.world
          2·
          10 months ago

          The solution is to try.

          In dev it’s called “fail fast”

          You try several solutions to the problem and iterate until you find the best working option then optimize.

          There’s no harm in an independent open source dev trying to solve a problem. Even if they fail there might be a kernel of useful code in a novel way.

          You absolutely shouldn’t just settle on one option without exploring several.

          But being stuck in a loop of over planning, waiting for legal, or outsourcing the problem is why everyone hates waterfall and just has small teams try with “agile” now.

          1% failure is just the start. You should never call a beta shit cuz it fails sometimes. Failure is part of learning and improving.

  • Awoo [she/her]@hexbear.netEnglish
    0·
    10 months ago

    Cool. After some testing Hexbear should run it. Not that the problem has ever been serious for Hex but still worthwhile and work that should absolutely be supported.

    • hikaru755@feddit.de
      2·
      10 months ago

      I think “legally” and “without constantly wanting to vomit” is the trickier question. From a purely ethical standpoint I don’t see a problem with taking CSAM that’s apparently already flooding Lemmy and using it to test whether your filter works before nuking it. At least as long as you’re making sure you’re not exposing anyone else to it.

    • Carighan Maconar@lemmy.world
      1·
      10 months ago

      There are I think official “training kits”? I remember reading about this, there are sets of data you can get to train CSAM detection with.

    • db0@lemmy.dbzer0.comOPM
      1·
      10 months ago

      Not for all csam and not at all for novel generative ai csam. It’s also not for all countries nor is it easy for everyone to join it and not everyone wants to be on cloudflare. Same is true for other tools like photodna