Lemmy.world (and some others) were hacked

Ruud@lemmy.worldmod to Lemmy.World Announcements@lemmy.world – 2319 points –

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.

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I heard that some instances were defaced. Any examples of this? I wasn't online this noon so I never got to see any action.

No need if it was JWT token. After you use your password to log in, the server send your browser/app a JWT token. It uses this token whenever it requests anything from the server, to show that your logged in for this session, and the server can look at the token and tell who it gave the token to, show it knows you're logged in.

All that is to say, logging out will mark any leaked token as no longer valid, and when you log back in you'll have a new, non-hacked login token.

I mean, I want to see screenshots of the "fake announcements" the hackers posted through compromised admin accounts

Oh sorry, I totally replied to the wrong comment lol

Was gonna go refind the right parent and reply, but tbh I'm in bed right now and too lazy for that, so I'm just leaving the non-sequitur there for anyone interested

It was some antisemitic bullshit. I have a screenshot, but it contains homophobic and racist phrases, so I don't think it's worth posting.

Can you send the screenshots through direct message to me? My curiosity is killing me

Thanks in advance!