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
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.
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.
But won’t custom emojis from remote instances still trigger the exploit?
Apparently not per the post-hack report: https://lemmy.ml/post/1901079
Apparently the custom emojis are rendered as static images when federated to outside instances so it’s clean.
I see a new lemmy-ui docker image has been pushed an hour ago, tagged
0.18.2-rc.1. Anyone know if it fixed the issue?Edit: yep, it’s fixed: https://github.com/LemmyNet/lemmy-ui/commit/e80bcf53acb8ce25ed5ef6b7eb16b90f0b07e8f1
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
- Inject exploit into a comment using custom emoji.
- Front-end parses the emoji incorrectly allowing JavaScript to be injected.
- JavaScript loads for everyone to views a page with the comment and sends their token and account type to the hackers domain.
- 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.
deleted by creator
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
onloadproperty 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.
It does look like most instances will be vulnerable judging by the fix. It’s not custom code; it’s in lemmy-ui proper.
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.
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
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.
Yeah, I’ve been scared to turn on 2FA with all the reports of people being locked out:
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.
XSS is a blanket term for vulnerabilities that allows attackers to inject client-side scripts. Looks like someone is already identified and submitted a pull request that contain a fix: https://github.com/LemmyNet/lemmy-ui/pull/1897/files
Aaaargh yeah using typescript doesn’t do jack when your API is stringly-typed. This erm wouldn’t have happened on the backend.
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.
As for the version, my instance reports it as
0.18.1-2-ga6cc12afeSo 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.
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!
Max-P doing the Lord’s work
For those not aware, the beehaw server did intentionally shut their instance down to avoid any issues.
See announcement here: https://hachyderm.io/@beehaw/110687918465426082
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.
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.
Looks like this thread is getting mass downvoted by bots btw
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.
we did it Reddit! /s
I saw this and laughed. Yes, that’s definitely how copyright works.
Twitter taking Threads down and posting this lol
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!
That’s fair. I shouldn’t have said “replace reddit.”
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.
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.
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.
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
Lemmy permission system is very limited, it’s a boolean for admin
this is what happens when socialists design hierarchies
lemmy.blahaj.zone got hacked too, looks like the same people
They also changed the allowed/blocked instances to allow threads.net and defederate lemmy.ml, just like they did on lemmy.world: https://lemmy.blahaj.zone/instances
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.
blahaj admins are aware and have the site down with a splash screen now
Links to this video: https://www.youtube.com/watch?v=Z1K4BUtHsO4
Yup they must of just put that up after I posted and @ the admins
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!
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.
I don’t think there will be too much fallout. Sites get hacked.
The “Hot” sort topic:
