PSA: Lemmy.world has been compromised! (Edit: Multiple Instances are down)

G59@lemmy.ml to Fediverse@lemmy.ml – 433 points –

FYI!!! In case you start getting re-directed to porn sites.

Maybe the admin got hacked?

edit: lemmy.blahaj.zone has also been hacked. beehaw.org is also down, possibly intentionally by their admins until the issue is fixed.

Post discussing the point of vulnerability: https://lemmy.ml/post/1896249

Github Issue created here: https://github.com/LemmyNet/lemmy-ui/issues/1895

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Yea, I switched to this alt. It appears to be one of the assistant admins accts. Seems like an old fashioned anon prank, to me, they're mainly just trying to make stuff offensive and redirect people to lemonparty.

So, y'know, old school.

I don't know if any data is actually in danger, but I doubt it. I don't see why assistant admins would need access to it.

All the bean memes are in danger! On a serious note, old-skool or not, it's a huge loss of trust in something the community-at-large is excited to see replace reddit.

Par for the course. This system will never be immune to things like that. That's part of what happens when you decentralize your power. Instead of a single target that can be made highly secure, you have a distributed array of targets.

People should certainly be engaging on here with full awareness of the reality of the Fediverse, not expecting reddit 2.0. We never will be able to offer exactly what they did. We'll be naturally worse in some areas and naturally better in others.

This is why I'm glad I made redundant accounts on multiple instances. When there are problems on lemmy.world, I can just hop on over to another. That's never been an option with Reddit.

Now if there was only a way to export or sync user settings like subscriptions, it would be perfect.

There's actually another thread on exactly this topic: https://lemmy.ml/post/1875767

Is there a way to link posts in the context of the reader’s instance? Like with !c community links?

It’s not great but if you copy the URL into your instance’s search, you can get to the post that way.

Yeah that’s what I’ve been doing. There was this great bot that was autocorrecting community links and I was hoping this was possible for post-links on Lemmy instances.

I don't think so, but I'd love to be proven wrong!

idk, im surprised it took this long. there's a huge variety of admin teams with varying degrees of security awareness and it's been over a month since the first big influx of users started. it'll happen again too and probably not before too long

In the 3 years Hexbear has been around it has been attacked A LOT because obviously far right chuds have an interest in messing with leftists but has not to my knowledge had an admin breach. At one point image embeds were completely disabled because they were handing over data they shouldn't though and risked exposing people to doxxing.

On the other hand, look at where we are. This is proof that one hack can't take down Lemmy.

True that. If you look at posts on lemmy.world though, it's clear their users (which is like 50% of Lemmy) have zero clue they're defederated ATM, and probably many that don't know it's compromised.

Federation and decentralization are not Web 2.0 concepts. Just like people who first learned what a tweet and a follow were and all the other concepts of those social media platforms, they'll learn the new paradigm. Or they won't and we'll stick to 2.0 platforms.

If there is a vulnerability in the software, it’s entirely possible for a single attack to take everyone down. All the instances are known and easily discovered.

i did switch from reddit to lemmy.world because i expected it to be a safe alternative that would atleast pay a lot of attention to security. so yes, the trust in security is broken a lot with this. especially since it happend so soon after so many people joined. i already think about maybe making my own instance to keep my account safe in the future.

My concern is that configuring the site to automatically redirect users sounds like they have pretty large control over the site - the kind of control that I would assume is usually limited to users with root access on the server.

Obviously hope nothing of value is lost and that there is a proper off-site backup of the content.

Edit: See Max-P's comment, it looks like the site redirection was accomplished in a way that IMO suggests they do NOT have full control over the site. We'll obviously have to wait for the full debrief from the admins.

If it was just DNS that doesn't mean too much. If it was just DNS it seems to be back up. It's like changing the number in a phone book.

It was a JavaScript injection to the site's sidebar and top announcement section

Yeah the "redirect somewhere else" attack definitely doesn't necessarily require any particular control of the site. Usually it's noticing that you can trick some text into being run as Javascript, instead of interpreted as text... And then you just stick in a cheeky little <notarealscript>window.location = "https://www.badsite.horse"</notarealscript> into that spot.

Then every time that comment, username, (in this case apparently) custom emoji, etc. gets loaded, whoops, the code runs and off you go!

So no control of the site is required at all.

I don't see why assistant admins would need access to it.

because it's easier than figuring out what permissions they actually need

probably even the top admin don't, it's gonna be encrypted, so even they don't know your password(except if they changed the code to store it in .txt) but always use differnt password in the internet

Nothing is encrypted except a user's password. If you have access to the database you can replace that with a known password hash.

Main instance hacked? Time to use an alt!

The first hack is a rite of passage for every site that gets big. It means we've been recognized!

Luckily, this seems to be a standard troll (with some tech knowledge) - they've defaced the site and put redirects to shock sites, rather than injecting actual malware or quietly collecting everyone's passwords. This could be much worse.

I tried to reproduce the exploit on my own instance and it appears that the official Docker for 0.18.1 is not vulnerable to it.

It appears that the malicious code was injected as an onload property in the markdown for taglines. I tried to reproduce in taglines, instance info, in a post with no luck: it always gets escaped properly in the <img alt="exploit here"> property as HTML entity.

lemmy.world appears to be running a git commit that is not public.

I actually consider it good news that the redirection is happening this way (something that can be done just by having the lemmy credentials of an admin) vs something indicating they have access to the server itself.

Yep, same. It was also the most likely scenario.

It looks like it was an individual admin getting hacked. Not good but not the worst. Most fallout will probably be whether their security practices were sufficient for an admin and whether lemmy has good enough contingencies for this sort of thing. Lemmy’s 2FA is probably a hot issue now though.

Yeah, I've been scared to turn on 2FA with all the reports of people being locked out:

Yeah, the Lemmy 2FA implementation sucks. It only works in certain authenticators - Authy not being one of them. Google Authenticator does work and apparently so does the iOS keychain (but can't confirm that one).

Best way to do it is to enable it and set it up but keep the settings window open, then open a separate incognito window and try to log in. If your 2FA code doesn't work, go back to the other settings window and disable it.

I am using 2fas with no issue and set it up using the method you described. So far, so good...in case anyone needed a vote of confidence!

The JWT are likely a hot issue, already some Issues on GitHub about them not being revoked properly.

Oh man, that would be brutal if they are resetting the password and it isn't kicking the attacker out...

That's probably what happened here because they did revoke the admin's access, but it continued.

JWT issue opened 4 days ago: https://github.com/LemmyNet/lemmy/issues/3499

The issue does say changing the password should kick the user out, but yeah, still not good.

This issue from 2 weeks ago was the one I was thinking of, it's worse: https://github.com/LemmyNet/lemmy/issues/3364

Oh man this one is SO much worse. If this is what is going on the only way to kick out the hacker will probably be to manually alter the DB. Yikes.

I hope the admin team is aware of this - not sure how one would even contact them.

Well, provided top level admin access to the server is still protected, a manual DB change ought to be rather doable right?

As for contacting the admins ... the lead admin, ruud, is on mastodon and also admins one of the largest mastodon instances: mastodon.world. They are Dutch however, which means they're likely asleep right now.

All of which raises the broader point about what good admin practice is. This is something the fediverse needs to get better at. In this case, as a bare minimum, every admin should be reachable at a location outside of their own instance.

Ideally, IMO, there'd be an "admin backline protocol" of some sort, where it's super easy or even automatic that every admin of every instance can have an account on any instance they federate with for the purposes of communication etc.

The hacked MichelleG account actually commented that it did not have MFA enabled lol. This was on the lemmy.world shitpost community, on one of the posts making memes about the situation. Hilarious that the hacker decided to share that.

OK good to know that the server itself is unlikely to be compromised. I'll be changing passwords to all my accounts once this blows over.

It seems the database and the server itself is not compromised? Just an admin account that used to post a markdown XSS exploit?

Pretty much, and it's not even XSS (it's not cross-site), it's just plain basic HTML injection breaking out of Markdown. At least as far as I was able to find.

Last I saw, they were on 0.18.1, unless a very recent update was installed. Do you happen to have a full list of domains they were redirecting to? Just want to be sure they were only going to "harmless" offensive sites, and not something worse.

Only lemonparty (which then redirects to chaturbate) and the pedo image hosted in the pictrs of lemmy.world itself. I saw no evidence of anything else, as people said, it's a pretty oldschool type of hack to disturb not spread malware.

But I didn't dig that much further than that, and it's only a snapshot of what I gathered before it got fixed. I Ctrl+F "lemonparty" in view source and pasted the JSON in VScode and that's about it. Didn't dig much deeper if that was just a red herring.

Thanks for digging in and sharing your findings!

As for the version, my instance reports it as

0.18.1-2-ga6cc12afe

So it seems to be using some extra patches, but I can't find that commit on GitHub which indicates it might not be public, or cherry-picked locally.

So with this in mind, either it's just innocent performance patches, or someone potentially also introduced the markdown vulnerability.

Although it's also entirely possible I suck and wasn't able to reproduce it correctly/had wrong quoting or something. Hopefully the devs can shine some light in the details.

How did it happen and what does this mean for me as a user of lemmy.ml who also follows people on lemmy.world?

One of the admin accounts appears to have been compromised. The owner/other admins appear to be aware now because that account had its admin access revoked and offending posts are being removed.

Definitely opens up a big question about the security of Lemmy instances that I am sure will be discussed over the next few days.

I wouldn't assume reasons why or that it's fixed until that consensus has been more widely reached.

More time will definitely be needed. I'm glad they caught it and acted quickly enough to prevent more vandalism from occurring, but until we know how the account was compromised and what else they may have gotten in the process, it's still a situation to keep an eye on.

Definitely opens up a big question about the security of Lemmy instances that I am sure will be discussed over the next few days.

They added 2FA login to lemmy in one of the newer updates. Probably pretty pertinent for any admins to use it....

It’s buggy and missing some key checks to make sure it’s working when you set it up.

Real risk of locking yourself out of your account.

oh, really? maybe i'll turn mine off then.....Thanks for the heads up!

Mostly a risk on initial setup.

I’ve been waiting a bit for it to stabilize and just using huge random passwords

If you're using a password manager you'd be doing this for every site and without even having to think about it. Bitwarden is a great choice.

I like KeePass. Bitwarden currently has an nginx exposure in the Dockerfile published in their git repo (may have been fixed since a couple of days ago). That said, I used Bitwarden for many years and switched out of an abundance of paranoia, and am definitively not recommending against it. Just basically use one of the following:

  • Bitwarden
  • KeePass
  • 1password

And stay far the fuck away from LastPass

my uni is currently still recommending lastpass as of now, tho I’ve heard they might be looking for alternatives …

Let your classmates know that last pass has semi permanently damaged their trustworthiness by trying to hide a security breach, and then downplaying the severity of the breach, and that your University's security recommendations are intrinsically suspect as a result

I don't know that 1password should be on that list. The first two are free and open source. The last one is paid and proprietary.

Don't put your credentials in the hand of a company that requires you to trust them to not fuck up. Everyone thought LastPass was great until they weren't

Also I believe this was achieved through cookie stealing, which 2FA would not have helped

They really need to improve their 2fa implementation

Not a whole lot - you might see some spam being federated from lemmy.world but I'd expect the lemmy.ml and lemmy.world admins will fix it, and them clean it up.

That's probably good stress test to figure out how to handle that.

God damn, spez-funded hacker groups already is trying to disrupt the resistance.

Fuck spez

This is going to turn into some obligatory response.

"Thank you everyone for coming together to discuss the planned future for the news community." Everyone: "Fuck spez."

Hmmm. Don’t know what the fall out of this will be. But a lot of lemmy is on that server. Unfortunately. Maybe we’ll learn a lesson in the value of decentralisation.

Ruud also runs mastodon.world, FYI.

This is why it makes sense for communities to not all pile into one instance, it gives one instance admin too much power and responsibility over everything.

mastodon.world seems okay, but whos to say where the silos are between that and lemmy.world.

was just some of the admin in the lemmy, i don't think they share the same admins

lemmy.world was briefly back to normal and there had been a post saying that everything was fine now - it's not.

The site has just started doing the same thing again.

Please do not try using lemmy.world for the time being.

the post saying everything was fine now was coming from the same account that was originally compromised

Lol so how do you expect to be notified then? You don't think they can get their account back? They'll get it back eventually.

They have multiple admins. The expectation would be for one of the non compromised admins to make the announcement. It's a trusted channels thing

i just got logged out of my account from Jerboa and can't login anymore. my is completely wiped from my app now.

edit: okay seems the admins have taken down lemmy.world and thats probably why it happend in the app. but its weird that it just wipes the login and data of the instance in the app.. weird.

My self hosted instance has hiccups sometimes and Jerboa just doesn't handle it super well. You can swipe away the app and reopen once the server is back and it should come right back up.

Jerboa tries to log in with session info passed to the server, if the server doesn't respond properly then it just calls you Anonymous, because it can't acquire your username and info. That's probably what's happening.

oh, okay. didn't knew that. i expected that it saves the login information locally (encrypted) and then uses this to login.. and if there is an error, that it just says "login error" or something.. with the option to retry.

it's weird that it looks like the whole login data just gets wiped. confused me a lot since it also said Anonymous as my user etc.. really thought first my account got hacked after all that issues.

I'm not using your app, I'm still learning Connect but ran into similar sounding confusion. Maybe yours is acting the same way: Connect puts an option in the settings to switch which instance(.world/.ee/.ca) it's running on, and each option will show its own list of users in the apps main sidebar. I switched and thought I lost all my login info, but it was there when I switched back. I maybe wouldn't try switching to .world right now, but if that's how your app works maybe it's all still there waiting.

Being a part of Lemmy in these early days has been kind of interesting, seeing all of the bugs and bits that will be ironed out over time. One day when Lemmy is as old as Reddit it will all be folklore. Maybe.

This'll definitely be remembered. It's good for us, we needed the wakeup call.

lemmy.blahaj.zone got hacked too, looks like the same people

https://lemmywinks.xyz/post/320087

Huh... so this probably is more sophisticated than a single acct breach then. Lovely.

Yeah, I'd recommend any server admin that doesn't have 2FA turn it on ASAP until we know what their exploiting

Looks like the accounts were compromised by stealing their cookie - something 2FA can't stop.

Still should have it on, though.

4AM in the Netherlands where the instance owner Ruud lives... hopefully his assistant admins can clean it up, but it might be a bit before he even knows anything is wrong.

GitHub PR fixing the bug: https://github.com/LemmyNet/lemmy-ui/pull/1897/files

If your instance has custom emojis defined, this is exploitable everywhere Markdown is available. It is NOT restricted to admins, but can be used to steal an admin's JWT, which then lets the attacker get into that admin's account which can then spread the exploit further by putting it somewhere where it's rendered on every single page and then deface the site.

If your instance doesn't have any custom emojis, you are safe, the exploit requires custom emojis to trigger the bad code branch.

I'm not particularly familiar with XSS but I'm curious how a frontend exploit can compromise an instance?

Presumably the injected XSS stores the admin's JWT somewhere for the exploiter?

Then using that JWT they can effectively login as the admin which gives them access to whatever admin dashboard there is, but does that actually compromise the backend at all?

edit: for anyone curious there's a bit of a breakdown of how it works here: https://feddit.win/comment/244427

  1. Inject exploit into a comment using custom emoji.
  2. Front-end parses the emoji incorrectly allowing JavaScript to be injected.
  3. JavaScript loads for everyone to views a page with the comment and sends their token and account type to the hackers domain.
  4. Hacker parses received tokens for admins and uses that to inject redirects into the front page of the Lemmy instance.

To answer your other questions:

  • IMO there probably should be better parsing to remove this stuff from the back-end, so I'm not sure the front-end solution is the complete solution, but it should get things largely under control.
  • Back-end is theoretically not compromised besides needing to purge all the rogue comments. Attacker presumably never had access to the server itself.
  • Probably needs to be a mass reset of ALL passwords since lots of people's tokens were sent during the attack, so their accounts could be compromised.

The admins now appears to have taken down the backend in an effort to stop the defacing.

Don't know if this will be relevant at all, but I'm almost hoping this will force Lemmy devs to abandon the obscure markdown crate they use for pulldown-cmark.

Using an obscure markdown implementation just because it supports spoiler tags always sounded like a silly decision to me!

Just went there and didn't immediately see anything out of the ordinary, but then was redirected to Chatroulette, lol yikes

Really hoping it's "only" redirecting to offensive sites, and not to malware. I got redirected a few times, before I closed my browser.

TBF modern browsers are remarkably secure from being a vector to pwn your computer these days.

EDIT: I don't endorse hanging out on a compromised lemmy.world. Focus on the implication for the bigger lemmyverse though. A hack coming through to you is unlikely.

You can't get malware or viruses just by visiting a site

The "Hot" sort topic:

I'm seeing zero comments come out of Lemmy.world in the past 15 minutes, app users shouldn't have been redirected... and users commenting from other servers should be going to communities homed there. I wonder if they shut off federation. I normally see over 10 comments a minute: https://lemmyadmin.bulletintree.com/query/comments_ap_id_host_prev?output=table&timeperiod=15

Last post received in my instance from them was over an hour ago. I usually see one or two a minute. Comments stopped at the same time and those are usually about every 5 seconds.

Hmm. They seem to have cleaned up a lot of things by now. If federation is an issue that might something the hacker did? Though pausing federation as a precaution makes sense.

Looks like this thread is getting mass downvoted by bots btw

It was cleaned up on the home page, but now back to being defaced as of this comment time.

Another user on the site confirmed this:

Oh wow again? 10 min ago it was clean! The .world admins are having a productive day lol

Now I'm unable to open lemmy.world, even on liftoff. Mods must have taken it down.

Same here. Seems to be toast through the liftoff app but I haven’t visited the site since the news broke. Liftoff was working an hour ago when it first happened.

It appears that the deface attack is back in full swing (racial slurs and all the redirects)

Time to make an alt! Been thinking about switching instances anyway, so this is a nice test. Hope the situation gets resolved soon.

Lemmy.world front page is back up, but I am now logged-out

@RoundSparrow @G59 is it safe to log in now?

They still have fake content on the front page. In a bogus community.

@RoundSparrow darn! welp, imma wait til tomorrow, many instances have decided to shut down preemptively anw.

Yep ... lemmy is home sick today. It has gone to the Doctor and should hopefully get better soon.

Looked like the admin u/MichelleG over there got hacked. That account posted a couple stickied posts and then all the css and links started changing on the site.

You would think an admin account would have 2fa enabled (unless the hack was due to a security issue in lemmy itself, but it doesn't seem to be the case).

Just clicked into Lenny.world and saw “site has been seized by Reddit for copyright infringement “

I really hope they have backups in place.

I was once doing work at a company that provided tech support and security for local businesses. There were a couple big instances of the companies being hacked with ransomware etc. On every occasion, we of course ask, "when was your last backup done?" And without fail, every one of them always responded, "backup?"

Oof. Oh well, at least they’re getting recognized I guess.

I decided to check it and it tells me that 'The site has been seized by Reddit for copyright infringement'.