While I was asleep, apparently the site was hacked. Luckily, (big) part of the lemmy.world team is in US, and some early birds in EU also helped mitigate this.
As I am told, this was the issue:
- There is an vulnerability which was exploited
- Several people had their JWT cookies leaked, including at least one admin
- Attackers started changing site settings and posting fake announcements etc
Our mitigations:
- We removed the vulnerability
- Deleted all comments and private messages that contained the exploit
- Rotated JWT secret which invalidated all existing cookies
The vulnerability will be fixed by the Lemmy devs.
Details of the vulnerability are here
Many thanks for all that helped, and sorry for any inconvenience caused!
Update While we believe the admins accounts were what they were after, it could be that other users accounts were compromised. Your cookie could have been ‘stolen’ and the hacker could have had access to your account, creating posts and comments under your name, and accessing/changing your settings (which shows your e-mail).
For this, you would have had to be using lemmy.world at that time, and load a page that had the vulnerability in it.
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
Could you please link the issue? Thanks!
https://github.com/LemmyNet/lemmy-ui/pull/1897/files found it myself
yup that’s the one
what I find weird is that the “fix” still focuses only on the front-end, the issue is still that unescaped HTML is being stored in the database and still trusting the front-end is nuts
I mean, I’m pretty sure that for an XSS attack that’s fine. The entire problem is that somebody posts e.g. a comment that contains code that is automatically run in users’ browsers. If you make the front end just not execute that code then it’s fine. Who cares what’s stored in the back end?
I mean, it would still be better to have multiple fail-safes, and they probably should still sanitize text entering the database.
But this is sufficient for a quick fix.
Let me introduce you to my friend, Little Bobby Tables… :)
ALWAYS SANITISE!
I think people are forgetting that it’s somewhat obvious the hackers or whomever, I don’t really care honestly are Lemmy users considering they did this at night and got into the site so quickly to begin with, they’d have to have been familiar with it to get into it as fast as they did.
If anything everything should be fixed.
For sure it is sufficient for a quick fix. But a Lemmy post can be posted not only on Lemmy but on other front ends (like kbin, mastodon, and many others) and they can suffer from a similar attack due to the backend storing and forwarding the bad content. So, it should not be stored as it is in the backend
I think the main developers are aware of either of them but I’m not sure, haven’t seen anyone site admin wise talk about this mess.
This discussion on the original bug report does talk about the back-end needing a fix as well.
The devs are aware
I think it makes sense to escape as close as possible to the context where the data will be used, see https://benhoyt.com/writings/dont-sanitize-do-escape/
Oofof… That’s not suppose how we announce vulnerabilities…