PSA: We're back, here's a post-mortem! (beehaw.org)

submitted 1 year ago* (last edited 1 year ago) by Lionir@beehaw.org to c/support@beehaw.org

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Hi Beeple!

Here's a vague version of events :

11PM EST: Lemmy.world got hacked
12:20AM EST: Blahaj.zone got hacked
12:25AM EST: I shut down the server
12:30AM EST: I make announcements to tell people about this
12:45AM EST: I have an idea of what the problem is but there is no fix
2:20AM EST: I go to sleep
8:50AM EST: The server is booted back up, steps are applied to mitigate issues (Rotating JWTs, Clearing DB of the source of vulnerability, deleting custom emoji), UI is updated with the fix, CSP and other security options are applied
11:40AM EST: We start testing things to make sure are working And well, now here we are.

If you have issues logging in or using an app:

Log out if you somehow are still logged in
Clear all cache, site data, etc.
Hard refresh Beehaw using CTRL+F5
Log back in.

If you still have issues, write to us at support@beehaw.org

To be clear : We have not been hacked as far as we know, we were completely unaffected. This was done preemptively.

Oh yeah, in case, you haven't, this is a good opportunity and reminder to follow us on Mastodon as the communication line was still up despite Beehaw being down : https://hachyderm.io/@beehaw

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[-] comicallycluttered@beehaw.org 3 points 1 year ago

Agree with everyone else. Thanks for shutting it down.

I'll most likely do it anyway, but do you think password changes are necessary at this point?

[-] Lionir@beehaw.org 3 points 1 year ago

I don't think this is necessary.

We had no messages on our database that had the vulnerability though some were federated from blahaj in the aftermath. The JWT, which is your session token, was changed as well so it seems very unlikely to me that this needs to be changed. There's no reason to believe the attack could've given access to passwords.

[-] abhibeckert@beehaw.org 5 points 1 year ago* (last edited 1 year ago)

I don’t think this is necessary.

I'd add that it's basically useless. From what I've seen, resetting your password doesn't even invalidate previously issued JWT tokens, which would be the only reason to do it. But of course, you've already reset them all and so has lemmy.world.

[-] mainfrog@beehaw.org 3 points 1 year ago

A password reset probably should invalidate all previous JWT tokens.

[-] jarfil@beehaw.org 4 points 1 year ago* (last edited 1 year ago)

We had no messages on our database that had the vulnerability

This is interesting. I actually commented about the use of emojis/emotes a couple days ago on a post on !foss@beehaw.org made by a federated user from lemmy.one, that has since been removed (😕), but I still have the bookmarked comment in which I copied the raw embed for the remote emote image in the federated comment I was responding to.

Do I understand it correctly, that the latest fixes to stop the code injection, will still allow remote image embedding, so something like an "emote picker extension to embed animated GIFs from a remote server and/or remote instance's emoji list" would still be doable and wouldn't pose any risk?

Or would such picker still have to include measures to prevent offering embeds with potential exploits?

[-] Lionir@beehaw.org 3 points 1 year ago

Remote image embedding is not the issue, remote custom emojis would not have been an issue either. The issue, from my understanding, is that the way local emojis are rendered allowed for an XSS exploit.

You can look at the PR which fixed this issue if you have a better understanding of these things than me : https://github.com/LemmyNet/lemmy-ui/pull/1897/

I believe such a picker would be fine.

[-] jarfil@beehaw.org 3 points 1 year ago* (last edited 1 year ago)

I see, so the prior emoji handling rendered content directly from the comment, instead of making sure it was strictly what was defined for the local emoji; that was a weird choice. Now they've also added a sanitizer wrapper to all of it in: https://github.com/LemmyNet/lemmy-ui/pull/1906

I guess the only downside of a picker that used the non-emoji image renderer, would be the loss of emoji CSS formatting.

[-] tanglisha@beehaw.org 3 points 1 year ago

From what I can tell the whole point to the css class/formatting was controlling the size of the emojis. Depending on where they came from, I could see some being of random size and shape. Admins might not have the time or know-how to shrink them down, so css seems like a reasonable compromise as long as the files aren't huge.

I'm kind of bothered that the only fix seems to be on the frontend. Unfortunately, I haven't been able to stick with Rust long enough to take a reasonable crack at figuring out how to help on the backend. Input and output sanitization should ideally be handled in both places.

[-] jarfil@beehaw.org 2 points 1 year ago

Lemmy's backend is kind of curious, in that it does the bare minimum to move content around and add some metadata fields.

For example, did you know that "deleting" a comment, only marks a "deleted: true" field, while the comment is still pushed in full to the frontend? Same thing happens with banned/mod removed comments, they just get marked as "removed: true" but otherwise still get pushed to the client, and the user can still edit them.

All the display processing is done in the frontend, or whichever app you happen to use.

[-] tanglisha@beehaw.org 0 points 1 year ago

I can maybe see marking it as deleted in case someone wants to creat undelete functionality later. I don't agree with it, but I can see why someone would do it.

It's just weird to still push it to the frontend.

Same with the removed stuff. All of that should be handled on the backend and never even sent to the frontend. Sometimes the reason for deletion is something you don't want getting grabbed by someone who is bored and poking around in developer tools, like doxxing information.

Since I don't have the time to do anything about it, though, I guess I don't have a place to complain. I have strong feelings about this stuff, but there's a limit to the number of things a single person can work on. If I were to hop on an open source project this minute, it would be helping migrate Cursorless to an LSP.

[-] jarfil@beehaw.org 0 points 1 year ago* (last edited 1 year ago)

There is an undelete feature, at least the Liftoff app has it.

Right now, the only effective way to delete a comment, is to edit and blank it, then you can delete it (well, the content, you still get shown as the author). The bright side is that even when the comment gets mod-deleted, you can still edit it... and everyone can still read it in the JSON... wait 🤔

someone who is bored and poking around in developer tools

No need, just view source. In the Liftoff app there is a "nerd stuff" option where you can also read the content.

Anyway, once a comment gets federated, it's out of the original user's control, can really take it back.

[-] tanglisha@beehaw.org 1 points 1 year ago

Hey, I wanted to thank you for this exchange. I learned a lot about lemmy.

[-] jarfil@beehaw.org 2 points 1 year ago

Glad to be of assistance. There's plenty of it I still haven't looked into, though.

[-] Cube6392@beehaw.org 2 points 1 year ago

To add onto what @Lionir said, you'll never be wrong to change your password, even if much like in this case it isn't warranted. For future reference, my recommendation is "if you have to ask, rotate your password." Finding out later you didn't have to is so much better than finding out later you should have

[-] abhibeckert@beehaw.org 3 points 1 year ago* (last edited 1 year ago)

I disagree - rotating passwords comes at a cost especially for people who don't use a good password manager (and that is basically everyone). It's security theatre and generally creates distrust between people offering security advice and the people who (hopefully) are listening.

There are times when it should be done, but don't do it without a reason.