cross-posted from: https://jamie.moe/post/113630

There have been users spamming CSAM content in !lemmyshitpost@lemmy.world causing it to federate to other instances. If your instance is subscribed to this community, you should take action to rectify it immediately. I recommend performing a hard delete via command line on the server.

I deleted every image from the past 24 hours personally, using the following command: sudo find /srv/lemmy/example.com/volumes/pictrs/files -type f -ctime -1 -exec shred {} \;

Note: Your local jurisdiction may impose a duty to report or other obligations. Check with these, but always prioritize ensuring that the content does not continue to be served.

  • @ludrol@bookwormstory.socialEnglish
    1•1 year ago

    I checked and there shouldn’t be any images stored on the server when running lemmy 1.18.4. The post was made in high emotional distress and shouldn’t be taken at a face value. If the posts are bothering you I advise purging the posts in question. (I have already done that)

    • JamieOPEnglish
      3•1 year ago

      I’m on 1.18.4, once I deleted the most recent images, the former CSAM posts(among others) became broken images. So yes, it was pulling from local disk cache. Then I took care of the posts themselves after the content was invalidated.

    • hitagiEnglish
      0•1 year ago

      How did you check this? From my understanding, images from external servers are copied (and transcoded) over locally. At least in my server (running 0.18.4), they do.

          • RentlarEnglish
            0•1 year ago

            Let me try to figure this out. The first is a photo uploaded to lemmy.world, the second is a photo originally uploaded to lemmy.nz, both posts are in a federated version of lemmy.world’s shitpost community.

            This is just a theory, but perhaps images hosted on the same server as the federated community will directly link, whereas images uploaded somewhere other than the federated community will be copied into cache, presumably in case the original host shuts down unexpectedly? See if this is the case?

            • hitagiEnglish
              2•1 year ago

              images hosted on the same server as the federated community will directly link

              https://ani.social/post/288601 - This image is uploaded from a user on the same instance as the federated community (lemmy.world) but the image is cached.

              images uploaded somewhere other than the federated community will be copied into cache

              https://ani.social/post/285354 - This image is uploaded from a user on a different instance (lemm.ee) from the federated community (lemmy.world) but the image is not cached.

              The behaviour is pretty weird. Hopefully we can disable image caching/copying-over-locally so we don’t have to deal with problematic images hosted by other instances.

  • DandroidEnglish
    1•1 year ago

    I got lucky. I am not subscribed to this community, and I am the only person on my instance. But what if I was subscribed and hadn’t seen this post? This is too much responsibility for me.

    I just shut down my instance until we can disable cached images. If that never happens, then I’m not bringing it back up.

    Shout-out to https://github.com/wescode/lemmy_migrate. I moved my subscriptions over in a minute or two, and now, other than not having my post history, it’s exactly the same.

    • JamieOPEnglish
      2•1 year ago

      At this point, the community is clean. So unless more is posted, then you should be good. If someone searched for the community and caused a preview to load while the content was active though, then it could be an issue.

  • @idle@158436977.xyzEnglish
    0•1 year ago

    I went ahead and just deleted my entire pictrs cache and will definitely disable caching other servers images when it becomes available.

  • @drcobaltjedi@programming.devEnglish
    0•1 year ago

    I was looking into self hosting. What can I do to avoid dealing with this? Can I not cache images? Would I get in legal trouble for being federated with an instance being spammed?

    • JamieOPEnglish
      2•1 year ago

      Not really. You could technically locate the images and determine precisely which ones they are from their filenames, but that means you actually have to view the images long enough to pull the URL. I had no desire to view them for even a moment, and just universally removed them.

      As mentioned in my edit above though, ensure you are in compliance with local regulations when dealing with the material in case you have to do any preservation for law enforcement or something.