Self Hosted - Self-hosting your services. @lemmy.ml Jamie @jamie.moe 1 yr. ago

WARNING: Lemmy Self-Hosters, There Have Been CSAM Attacks taking place against !lemmyshitpost@lemmy.world

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.

30 comments

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.
- 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.
  
  Would rm be okay if you regularly fstrim?
- The only 100% foolproof-way is to physically destroy the server disk where that image is stored. Do not place those drive fragments in a recycling center, landfill.
- Wouldn't the images still be stored on Lemmy.world's servers? I thought federation simply meant you host a link to it (still bad, but it just goes away if you rm the post).
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.
- [This comment has been deleted by an automated system]
  
  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.
  
  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.
- yeah this has got me second guessing hosting my own instance as well.
  
  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.
- 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.
  
  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
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.
What's a CSAM attack? Sounds so serious, but I've never heard of it.
- Spamming pornographic depictions of minors
- I had to google it but that stands for child sexual abuse material
  
  Oh, damn.
- It is where scum spam a site with illegal images, which can result in the site being taken down and in some instances the site owners being prosecuted.
  
  Depending on where you live you may have a legal obligation to report the incidents and to prove actions taken to remove the content.
  
  related in the US: safe harbor laws
What kind of depraved piece of shit does this?
- Permanently Deleted
Pedophiles ruin everything.
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.
From what I understand from federation, shouldn't the images still live on whatever server they were uploaded to? Sure the post gets federated and now you have links to csam on your server but you just need to delete the post, not the image, unless the attacker uploaded it to your pict-rs (how?).

To me this is a cornerstone of federation, it ensures both security for federaters and optimal disk space usage at the cost of bandwidth usage for popular hosters.
- Permanently Deleted
  
  So it does, disregard what I said
If anyone is looking for the NCME reporting registration.
@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/

You've viewed 30 comments.