2y ago

I just developed and published a script to clear your pict-rs object storage from potential CSAM.

GitHub - Haidra-Org/lemmy-safety: A script that goes through a lemmy pict-rs object storage and tries to prevent illegal or unethical content

I noticed a bit of panic around here lately and as I have had to continuously fight against pedos for the past year, I have developed tools to help me detect and prevent this content.

As luck would have it, we recently published one of our anti-csam checker tool as a python library that anyone can use. So I thought I could use this to help lemmy admins feel a bit more safe.

The tool can either go through all your images via your object storage and delete all CSAM, or it canrun continuously and scan and delete all new images as well. Suggested option is to run it using --all once, and then run it as a daemon and leave it running.

Better options would be to be able to retrieve exact images uploaded via lemmy/pict-rs api but we're not there quite yet.

Let me know if you have any issue or improvements.

EDIT: Just to clarify, you should run this on your desktop PC with a GPU, not on your lemmy server!

Linux and Tech News @lemmy.linuxuserspace.show

Strit @lemmy.linuxuserspace.show

2y ago

Lemmy Safety now supports cleaning local pict-rs storage from CSAM

github.com /db0/lemmy-safety

Selfhosted @lemmy.world

db0 @lemmy.dbzer0.com

2y ago

Lemmy Safety now supports cleaning local pict-rs storage from CSAM

github.com /db0/lemmy-safety

Fediverse @lemmy.world

db0 @lemmy.dbzer0.com

2y ago

I just developed and published a script to clear your pict-rs object storage from potential CSAM.

github.com /db0/lemmy-safety

106 comments

Hey @db0@lemmy.dbzer0.com, just so you know, this tool is most likely very illegal to use in the USA. Something that your users should be aware of. I don't really have the energy to go into it now, but I'll post what I told my users in the programming.dev discord:
that is almost definitely against the law in the USA. From what I've read, you have to follow very specific procedures to report CSAM as well as retain the evidence (yes, you actually have to keep the pictures), until the NCMEC tells you you should destroy the data. I've begun the process to sign up programming.dev (yes you actually have to register with the government as an ICS/ESP) and receive a login for reports.
If you operate a website, and knowingly destroy the evidence without reporting it, you can be jailed. It's quite strange, and it's quite a burden on websites. Funnily enough, if you completely ignore your website, so much so that you don't know that you're hosting CSAM then you are completely protected and have no obligation to report (in the USA at least)
Also, that script is likely to get you even more into trouble because you are knowingly transmitting CSAM to 'other systems', like dbzer0's aihorde cluster. that's pretty dang bad...
here are some sources:
https://www.law.cornell.edu/uscode/text/18/2258A
https://crsreports.congress.gov/product/pdf/LSB/LSB10713
https://www.missingkids.org/theissues/csam
https://www.cloudflare.com/service-specific-terms-application-services/#csam-scanning-tool-terms
https://developers.cloudflare.com/cache/reference/csam-scanning/#what-happens-when-a-match-is-detected
https://developers.cloudflare.com/cache/reference/csam-scanning/#what-action-should-i-take-when-a-match-is-detected
- Note that the script I posted is not transmitting the images to the AI Horde.
  Also keep in mind this tool is fully automated and catches a lot of false positives (due to the nature of the scan, it couldn't be otherwise). So one could argue it's a generic filtering operation, not an explicit knowledge of CSAM hosting. But IANAL of course.
  This is unlike cloudflare or other services which compare with known CSAM.
  EDIT: That is to mean, if you use this tool to forward these images to the govt, they are going to come after you for spamming them with garbage
  
  Cloudflare still has false positives, the NCMEC does not care if they get false positives. If you read some of those links I provided it wouldn't be considered a generic filtering operation, from how I'm reading it at least. I wouldn't take the chance, especially not with running the software on your own hardware in your own house, split from the server.
  I think you're not in the US? So it's probably different for your jurisdiction. Just want to make it clear that in the US, from what i've read up on, this would be considered against the law. You are running software to filter for CSAM, so you are obligated to report it. Up to 1 year jail time for not doing so.
- Ugh, what a mess. Thought about this for a while today and three thoughts started circulating in my head:
  Hire an actual lawyer and get firm legal advice on this issue. I think this would fall to the admins, not the devs. Maybe an admin who wanted could volunteer to contact a lawyer? We could do a gofundme for one-time consultation legal fees.
  Stop using pictrs completely and instead use links to a third party such as Imgur or whatever. They’re in this business and I’m sure already have dealt with it and have a solution. Yes it sucks that Imgur (or whatever third party) could delete our legitimate images at any time, but IMHO it’s worth it to avoid this headache. At any rate it offloads the liability from an admin. Of course, IANAL and this is a question we would want to ask a lawyer about.
  Needing a GPU increases the expenses for an admin significantly. It will start to not be worth it for quite a few to keep their instance running.
  Thanks for bringing up this point. This is obviously a nuanced issue that is going to need a well-thought-out solution.
  
  The GPU doesn't have to be high-end, and can run on someone's PC
  
  Depending on the country, those laws may be different. Here is a story of a guy who ran a TOR exit node in Australia who would have been protected as a company (law was later changed).
  https://lowendbox.com/blog/man-found-guilty-of-child-porn-because-he-ran-a-tor-exit-node-the-story-of-william-weber/
- the ridiculous part of it is, as I understand it, if you completely ignore your website and essentially never know that you're hosting CSAM then you cannot be held liable for it. But then, someone's probably literally gonna come hunt you down to tell you in person (FBI) lol. So probably best to not ignore it.
This is extremely cool.
Because of the federated nature of Lemmy many instances might be scanning the same images. I wonder if there might be some way to pool resources that if one instance has already scanned an image some hash of it can be used to identify it and the whole AI model doesn't need to be rerun.
Still the issue of how do you trust the cache but maybe there's some way for a trusted entity to maintain this list?
- How about a federated system for sharing “known safe” image attestations? That way, the trust list is something managed locally by each participating instance.
  Edit: thinking about it some more, a federated image classification system would allow some instances to be more strict than others.
  
  I think building such a system of some kind that can allow smaller instances to rely from help from larger instances would be extremely awesome.
  Like, lemmy has the potential to lead the fediverse is safety tools if we put the work in.
  
  Consensus algorithms. But it means there will always be duplicate work.
  No way around that unfortunately
- I'd rather have a text-only instance with no media at all. Can this be done?
  
  Yes it is definitely possible! Just have no pictrs installed/running with the server. Note it will still be possible to link external images.
- TBH, I wouldn’t be comfortable outsourcing the scanning like that if I were running an instance. It only takes a bit of resources to know that you have done your due diligence. Hopefully this can get optimized to get time to be faster.
As a test, I ran this on a very early backup of lemm.ee images from when we had very little federation and very little uploads, and unfortunately it is finding a whole bunch of false positives. Just some examples it flagged as CSAM:
Calvin and Hobbes comic
The default Lemmy logo
Some random user's avatar, which is just a digital drawing of a person's face
a Pikachu image
Do you think the parameters of the script should be tuned? I'm happy to test it further on my backup, as I am reasonably certain that it doesn't contain any actual CSAM
- This is normal . You should be worried if it wasn't catching any false positives as it would mean a lot of false negatives would slip though. I am planning to add args to make it more or less severe, but I it will never be perfect. So long as it's not catching most images, and of the false positives most are porn or contain children, I consider with worthwhile.
  I'll let you know when the functionality for he severity is updated
How do you even safely test scripts/tools like this 😵‍💫
- I'd bet there's a CSAM test image dataset with innocuous images that get picked up by the script. Not sure how the system works, but if it's through hashes then it would be pretty simple to add that to the script.
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:
Fewer Letters More Letters

CF CloudFlare
CSAM Child Sexual Abuse Material
DNS Domain Name Service/System
HTTP Hypertext Transfer Protocol, the Web
nginx Popular HTTP server
4 acronyms in this thread; the most compressed thread commented on today has 6 acronyms.
[Thread #88 for this sub, first seen 28th Aug 2023, 22:25] [FAQ] [Full list] [Contact] [Source code]
I don't host a server myself, but can this tool identify the users who posted the images and create a report with their IP addresses?
This could help identify who spreads that content and it can be used to notify authorities. No?
- No but it will record the object storage We then need a way to connect that path to the pict-rs image ID, and once we do that, connect the pict-rs image ID to the comment or post which uploaded it. I don't know how to do the last two steps however, so hopefully someone else will step up for this
Thank you for helping make the fediverse a better place.
Don't have a GPU on my server. How is performance on the CPU ?
- It will be atrocious. You can run it, but you'll likely be waiting for weeks if not months.
- the model under the hood is clip interrogator, and it looks like it is just the torch model.
  it will run on cpu, but we can do better, an onnx version of the model will run a lot better on cpu.
  
  sure, or a .cpp. But it will still not be anywhere near as good as a GPU. However it might be sufficient for something just checking new images
Worth noting you seem to be missing dependencies in requirements.txt notably unidecode and strenum
Also that this only works with GPU acceleration on NVidia (maybe, I messed around with trying to get it to work with AMD ROCm instead of CUDA but didn't get it running)
- Ah thanks. I'll add them
- to run on ROCm, you need a specific version of pytorch.
  but it is still in beta, i would not expect it to run well
  
  I know, I tried and ran into some problems there. I just pulled out my NVidia laptop and got it to go (slowly)
Not well versed in the field, but understand that large tech companies which host user-generated content match the hashes of uploaded content against a list of known bad hashes as part of their strategy to detect and tackle such content.
Could it be possible to adopt a strategy like that as a first-pass to improve detection, and reduce the compute load associated with running every file through an AI model?
- match the hashes
  It's more than just basic hash matching because it has to catch content even if it's been resized, cropped, reduced in quality (lower JPEG quality with more artifacts), colour balance change, etc.
  
  Well, we have hashing algorithms that do exactly that, like phash for example.
  
  Ah, of course - that's unfortunate, but thanks for the pointer.
Hi db0, if I could make an additional suggestion.
Add detection of additional content appended or attached to media files. Pict-rs does not reprocess all media types on upload and it's not hard to attach an entire .zip file or other media within an image (https://wiki.linuxquestions.org/wiki/Embed_a_zip_file_into_an_image)
- Currently I delete on PIL exceptions. I assume if someone uploaded a .zip to your image storage, you'd want it deleted
  
  The fun part is that it’s still a valid JPEG file if you put more data in it. The file should be fully re-encoded to be sure.
  
  As @Starbuck@lemmy.world stated. They're still valid image files, they just have extra data.
based db0 releasing great tools and maintaining a great community
Opened a relevant issue: https://github.com/LemmyNet/lemmy/issues/3920
Hey db0 thanks for putting in extra effort to help the community (as you have multiple times) when big issues like this crop up on Lemmy.
Despite being a pressing issue this is one that people also are a little reluctant to help solve because of fear of getting in trouble themselves. (How can a server admin develop a method to detect and remove/prevent CSAM distribution without accessing known examples which is extremely illegal?)
Another time being the botspam wave where you developed Overseer in response very quickly. I'm hoping here too devs will join you to work out how to best implement the changes into Lemmy to combat this problem.
Thanks for releasing this. After doing a --dry_run can the flagged files then be removed without re-analysing all images?
- Not currently supported. It's on my to-do
Thank you for this! Awesome work!
By the way, this looks easy to put in a container. Have you considered doing that?
- I don't speak docker, but anyone can send a PR
  
  I'll try it out today. I'm about to start my workday, so it will have to be in a few hours. Fingers crossed I can have a PR in about 16 hours from now.
This is awesome. Thank you for making it.
Any thoughts about using this as a middleware between nginx and Lemmy for all image uploads?
Edit: I guess that wouldn't work for external images - unless it also ran for all outgoing requests from pict-rs.. I think the easiest way to integrate this with pict-rs would be through some upstream changes that would allow pict-rs itself to call this code on every image.
- Exactly. If the pict-rs dev allowed us to run an executable on each image before accepting it, it would make things much easier
- You might be able however integrate with my AI Horde endpoint for NSFW checking between nginx and Lemmy.
  https://aihorde.net/api/v2/interrogate/async
  This might allow you to detect NSFW images before they are hosted
  Just send a payload like this
  
  curl -X 'POST' \ 'https://aihorde.net/api/v2/interrogate/async' \ -H 'accept: application/json' \ -H 'apikey: 0000000000' \ -H 'Client-Agent: unknown:0:unknown' \ -H 'Content-Type: application/json' \ -d '{ "forms": [ { "name": "nsfw" } ], "source_image": "https://lemmy.dbzer0.com/pictrs/image/46c177f0-a7f8-43a3-a67b-7d2e4d696ced.jpeg?format=webp&thumbnail=256" }'
  Then retrieve the results asynchronously like this
  
  { "state": "done", "forms": [ { "form": "nsfw", "state": "done", "result": { "nsfw": false } } ] }
  or you could just run the nsfw model locally if you don't have so many uploads.
  if you know a way to pre-process uploads before nginx sends them to lemmy, it might be useful
Can this be used with Mastodon as well?
- If it's using object storage, yes
Amazing work.
Just going to argue on behalf of the other users who know apparently way more than you and I do about this stuff:
WhY nOt juSt UsE thE FBi daTaBaSe of CSam?!
(because one doesn’t exist)
(because if one existed it would either be hosting CSAM itself or showing just the hashes of files - hashes which won’t match if even one bit is changed due to transmission data loss / corruption, automated resizing from image hosting sites, etc)
(because this shit is hard to detect)
Some sites have tried automated detection of CSAM images. Youtube, in an effort to try to protect children, continues to falsely flag 30 year old women as children.
OP, I’m not saying you should give up, and maybe what you’re working on could be the beginning of something that truly helps in the field of CSAM detection. I’ve got only one question for you (which hopefully won’t be discouraging to you or others): what’s your false-positive (or false-negative) detection rate? Or, maybe a question you may not want to answer: how are you training this?
- I'm not training it. Im using publicly available clip models.
  The false positive rate is acceptable. But my method is open source so feel free to validate on your end
  
  Acceptable isn’t a percentage, but I see in your opinion that it’s acceptable. Thanks for making your content open source. I do wish your project the best of luck. I don’t think I have what it takes to validate this myself but if I end up hosting an instance I’ll probably start using this tool more often myself. It’s better than nothing at at present I have zero instances but also zero mods lined up.
Now if you can make this work with mastodon, i'd be eternally grateful.😁
- It's software agnostic. So long as you're storing you're images in object storage, it should work
I think deleting images from the pictrs storage can corrupt the pictrs sled db so I would not advise it, you should go via the purge endpoint on the pictrs API.
- Nah. It will just not find those images to serve
  
  Interesting, when I tried a while back it broke all images (not visible on the website due to service worker caching but visible if you put any pictrs url into postman or something)
Can this be used with the Lemmy-easy-deploy method?
- This shouldn't run on your lemmy server (unless your lemmy server has a gpu)
  
  I can put one in..
anything worthy is illegal in the us, get gud! thankfully Lemmy is hosted in europe or any vps somewhere