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.

Update

Apparently the Lemmy Shitpost community is shut down as of now.

  • mlfh@lemmy.ml
    95·
    1 year ago

    If you aren’t going to fully wipe your drive in horrible events like this, at the very least use shred instead of rm. rm simply removes references to the file in the filesystem, leaving the data behind on the disk until other data happens to be written there.

    Do not ever allow data like that to exist on your machines. The law doesn’t care how it got there.

    • Mic_Check_One_Two@reddthat.com
      31·
      1 year ago

      Was going to say the same. Windows and Linux both use “lazy” ways of deleting things, because there’s not usually a need to actually wipe the data. Overwriting the data takes a lot more time, and on an SSD it costs valuable write cycles. Instead, it simply marks the space as usable again, and removes any associations to the file that the OS had. But the data still exists on the drive, because it’s simply been marked as writeable again.

      There are plenty of programs that will be able to read that “deleted” content, because (again) it still exists on the drive. If you just deleted it and haven’t used the drive a lot since then, it’s entirely possible that the data hasn’t been overwritten yet.

      You need a form of secure delete, which doesn’t just mark the space is usable. A secure delete will overwrite the data with junk data. Essentially white noise 1’s and 0’s, so the data is completely gone instead of simply being marked as writeable.

        • alanceil@lemmy.world
          4·
          1 year ago

          No, fstrim just tells your drive it doesn’t need to care about existing data when writing over it. Depending on your drive, direct access to the flash chips might still reveal the original data.

          If you want ensure data deletion, as OP said, you’ll need to zero out the whole drive and then fstrim to regain performance. Also see ATA Secure Erase. Some drives encrypt by default and have Secure Erase generate a new key. That will disable access to the old data without having to touch every bit.

        • Zacryon@feddit.de
          2·
          1 year ago

          TRIM tells the SSD to mark an LBA region as invalid and subsequent reads on the region will not return any meaningful data. For a very brief time, the data could still reside on the flash internally. However, after the TRIM command is issued and garbage collection has taken place, it is highly unlikely that even a forensic scientist would be able to recover the data.

          From: https://en.m.wikipedia.org/wiki/Trim_(computing)#Operation

          So: probably yes.

  • lea@feddit.de
    641·
    1 year ago

    I nuked my personal instance because of this :(

    Dealing with pictrs is just frustrating currently since there’s no tools for its database format and no frontend for the API. I half-expected this outcome but I hope it gets better in the future.

    • Skull giver@popplesburger.hilciferous.nl
      33·
      1 year ago

      I’m in the process of hopefully writing a tool to make deletion a bit easier, basically purging all the content not uploaded on my personal server. I can’t help but feel like pict-rs is not ready for prime time yet.

      There is no API endpoint to list all images known in the system. There is no direct connection between posts and images, or even images and users, even if they’re cached locally. This is way more painful than it needs to be.

      • Toribor@corndog.socialEnglish
        1·
        1 year ago

        Pict-rs has been the single largest pain of self-hosting a tiny Lemmy instance. I really hope things improve. I like hosting it myself but I can’t do it as a second job, having to figure out my own hacks and workarounds just to keep it running and not serving up illegal crap.

        • Skull giver@popplesburger.hilciferous.nl
          1·
          1 year ago

          About a month after I commented that, pict-rs added the external_validation URL for pre-processing. I haven’t looked into it myself, but Lemmy servers can now run images through a CSAM detector before uploading.

          Combining pictrs-safety and fedi-safety should help prevent the most immediate issues. However, fedi-safety requires a GPU for any kind of efficient processing, and I don’t have anything compatible available. I could waste many CPU cycles on running that stuff on the CPU, but I’m not going to bother with that.

          Once illegal crap makes it to your server, you need to check your local laws before deleting it. Some jurisdictions require you to keep the files (but deny access) for evidence, and require you to notify the authorities. This stuff is exactly why self-hosting social media sounds nice but sucks in practice.

          • Toribor@corndog.socialEnglish
            2·
            1 year ago

            Thank you! I was looking into running this a week or two ago when I was doing some maintenance but I gave up and shelved the project for later due to the complexity. My Lemmy instance is running in AWS and I’m going to have to put some work into my network setup on both ends to be able to connect to a computer with a GPU at home.

            I’m glad the community is working to resolve some of these issues. Hopefully some of this will get easier and more cost-effective.

      • clearedtoland@lemmy.worldEnglish
        21·
        1 year ago

        That finalized my decision to not self-host. I’m savvy enough to set it up but not enough to keep up with maliciousness like this. I’d never even considered a deliberate CSAM attack as a possibility - I thought it was just something (atrocious) users might inadvertently post.

        • SkyeStarfall@lemmy.blahaj.zone
          10·
          1 year ago

          You always gotta prepare for the worst case. It’s certainly why I am never going to bother with hosting something like this unless I’m serious about it akin to a job. If there’s even a remote chance of CASM getting on your machine, you gotta assume it will and be prepared to fight to prevent it/remove it.

    • fmstrat@lemmy.nowsci.comEnglish
      10·
      1 year ago

      Agreed, pict-rs is not ready for this. Not having an easy way to map URL to file name is a huge issue. I still don’t understand why non-block storage doesn’t just use the UUID it generates for the URL as a filename. There is zero reason to not have a one-to-one mapping.

      • ohai@subsubd.comEnglish
        2·
        1 year ago

        yeah, I just spent the last hour writing some python to grab all the mappings via the pict-rs api. Didn’t help that the env var for the pictrs api token was named incorrectly (I should probably make a PR to the Lemmy ansible repo). EDIT: Nevermind, seems there is one already! https://github.com/LemmyNet/lemmy-ansible/pull/153

  • UntouchedWagons@lemmy.caEnglish
    291·
    1 year ago

    I’m not surprised. It was quite common for shitheads on reddit to make an account, post a few comments on /r/againsthatesubreddits, then post CP on other subreddits to spin the narrative that AHS was trying to shut down hate subs.

  • thisisawayoflife@lemmy.world
    5·
    1 year ago

    Naive question here: would it be valuable to generate hashes of those images and provide them as a public database? Seems like it would be valuable to reject known images using some mechanism to prevent this from happening broadly. It wouldn’t stop someone from on-the-fly systematically editing/saving/uploading CSAM, but hashes are cheap to store and it would at least provide one barrier to entry.

  • Jaz-Michael King@mastodon.iftas.org
    1·
    1 year ago

    @Jamie some recommended reading here for hosting ActivityPub services: https://github.com/FediFence/fedifence/blob/main/LegalRegulatory.md

    Cloudflare has a free CSAM filter: https://developers.cloudflare.com/cache/reference/csam-scanning/

    IFTAS is working on an opt-in CSAM scanner for service providers, follow this account to be notified

    Lemmy moderators should fill out this needs assessment: https://cryptpad.fr/form/#/2/form/view/thnEBypiNlR6qklaQNmWAkoxxeEEJdElpzM7h2ZIwXA/