Very impressed by how quickly action has been taken by this and other instances to patch the issue.

I wish hackers would invest their time in clearing credit card debt, deleting hospital fees, or something else that actually serves the public good, instead of hacking ordinary people just trying to get by.

Thanks Ruud for fixing it! Just a reminder guys that If you are using a third party app you need to login again.

what steps are being taken to ensure it doesn't happen again? was any personal data compromised for users?

IMPORTANT ANNOUNCEMENT: My account was not among those hacked. Any random bullshit appearing in my post/comment history was written by me.

First - really good summary and sounds like everyone is working hard.

Cross posting the below comment.

Under GDPR if you have had a data breach you have a legal obligation to assess whether you need to report it and you must make the report within 72 hours of discovering the breach.

There are other types of reportable breaches too, I only mention data as it sounds most likely. You may or may not be subject to PECR which may also have been breached although less likely. I don’t really have enough familiarity with the regulation to discuss that one.

If you are not sure if there has been a breach you may also need to discuss it with the relevant body or make a report.

Please can you update what action you have taken regarding this and if the incident was reportable or not and the reasons why. Edit - from that new information, it sounds like this is a reportable breach.

For a full understanding, it would be good to know if you had 2FA enabled on the compromised account particularly as it had admin privileges and if so how 2FA was circumvented with this exploit.

It would also be good to know what measures you have in place to prevent the same or other malicious attempts on your Open Collective and Patreon accounts as issues with those are potentially more serious. They may not be vulnerable to this, but it is going to be reassuring to know there is good security practice, 2FA protection etc enabled and you have robust procedures in place.

Thanks for letting us know - this is the kind of transparency that I wish the world had more of!

So what happened:

• Someone posted a post.
• The post contained some instruction to display custom emoji.
• So far so good.
• There is a bug in JavaScript (TypeScript) that runs on client's machine (arbitrary code execution?).
• The attacker leveraged the bug to grab victim's JWT (cookie) when the victim visited the page with that post.
• The attacker used the grabbed JWTs to log-in as victim (some of them were admins) and do bad stuff on the server.

Am I right?

I'm old-school developer/programmer and it seems that web is peace of sheet. Basic security stuff violated:

• User provided content (post using custom emojis) caused havoc when processing (doesn't matter if on server or on client). This is lack of sanitization of user-provided-data.
• JavaScript (TypeScript) has access to cookies (and thus JWT). This should be handled by web browser, not JS. In case of log-in, in HTTPS POST request and in case of response of successful log-in, in HTTPS POST response. Then, in case of requesting web page, again, it should be handled in HTTPS GET request. This is lack of using least permissions as possible, JS should not have access to cookies.
• How the attacker got those JWTs? JavaScript sent them to him? Web browser sent them to him when requesting resources form his server? This is lack of site isolation, one web page should not have access to other domains, requesting data form them or sending data to them.
• The attacker logged-in as admin and caused havoc. Again, this should not be possible, admins should have normal level of access to the site, exactly the same as normal users do. Then, if they want to administer something, they should log-in using separate username + password into separate log-in form and display completely different web page, not allowing them to do the actions normal users can do. You know, separate UI/applications for users and for admins.

Am I right? Correct me if I'm wrong.

Again, web is peace of sheet. This would never happen in desktop/server application. Any of the bullet points above would prevent this from happening. Even if the previous bullet point failed to do its job. Am I too naïve? Maybe.

Marek.

Damn, I go to bed early and I miss everything! Thanks for the quick resolution and transparent disclosure, this place is great!

Thank you for your work 🙏

This is really good to see such transparency from admins

Love the transparency!

Good thing we all use randomly generated passwords for every account and always remember to change them every few months.

Can we get another admin to sign off on this being authentic? In other words, short of a signed GPG signature how do we trust announcements after a breach where admin accounts are compromised?

Thanks for the work. As a heads up it appears most of the block instances are back however I believe explodingheads is still missing which you may want to confirm.

EDIT: it has been added back to the block list.

So thats why MalwareBytes gave me this message yesterday.

the details of the vulnerability are already known now anyway since there's a fix that was proposed on the Lemmy GitHub so I don't think it will hurt others to talk about it

FYI: I had to clear my lemmy.world cookies in order to be able to successfully log back in.

(This was with Firefox)

(Edit: I also shift-clicked reload, which somebody pointed out does clean the cache for that page, so I also cleaned the cache).

How do we know that this isn't a fake announcement as well, trying to give us a sense of security???

Just kidding, thanks for letting us know! Thank god I haven't been too active the last few days! Can't afford my credentials being leaked, maybe I should be proactive and change my password anyways.

Thank the heavens the meme community stayed safe through this without my daily dose of cybersecurity memes idk how I would function ;)

Had to clear my browser catch to log in, Jerboa still shows as not logged in even after logging out which you do by clicking the hamburger menu then click the top banner to change/log out of accounts. This post is a test to see if my account works again via browser lol.

Edit: clearing app data/cache for Jerboa fixed the login issue.

Do we have any details on how Michelle's account was compromised? Right now in the GitHub issue about the vulnerability they're clueless about how the custom emoji exploit could be performed without first an already compromised admin account.

EDIT: yeah here's how: https://github.com/LemmyNet/lemmy-ui/issues/1895#issuecomment-1629326627

You do NOT need an admin account to do that. Any normal user could have done that.

Hopefully with more attention on the source code scary hacks like this doesn’t happen again.

One wonders how much spez paid for that hack.

Took me a bit to realize I actually had to log out and log back in on Jerboa since it looked like I was still logged in but some interactions didn't work

You guys really have my highest respect for spending so much time to keep this running, despite all the recent trouble and now even an attack.

Thank you very much <3 You guys are awesome and I really appreciate how publicly you deal with this.

Can I ask some possibly dumb questions?

1. What is JWT?
2. Was any private user data compromised, and if so will users be informed?
3. Is there anything regular users can do to avoid their data being compromised? For example, not accessing lemmy on certain web browsers?

Thank you!

I think this is a strong reminder: We shouldn't put all our eggs in one basket. This will happen again. Unlike Reddit, we don't need to concentrate all communities on one instance. We should all make an effort to spread out. Some other general use instances are:

• https://lemm.ee
• https://lemmy.one
• https://sh.itjust.works
• https://sopuli.xyz

Again, for those new, you can post content to any of these instances and interact with content from other instances at the same time, just like you can send an email from your Gmail account to your ProtonMail account.