Hey everyone, this exploit is present in the custom emoji feature of Lemmy. Because lemdro.id does not use custom emojis, we are not vulnerable at this time.
this post was submitted on 10 Jul 2023
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Some information I have posted to Lemmy.World:
I am not a super code-literate person so bare with me on this... But. Still please becareful. There appears to be a vulnerability.
Users are posting images like the following:
And inside hidden is JavaScript code that when executed can take cookie information and send it to a URL address.
Among other things. At this time if you see an image please click the icon circled before clicking the link. DO NOT CLICK THE IMAGE. If you see anything suspicious, please report it immediately. It is better a false report than a missed one.
I have seen multiple posts by these people during the attack. It is most certainly related to JS.
If it's onload then simply viewing the image runs that script. Yikes.
That's even worse, if Lemmy has a vulnerability like that it needs to get fixed ASAP... Also if that code actually works, I am going to have to secure my account.
I'd wager you're likely fine if you're using a mobile app when the affected image loads. Also, it appears they're stealing auth tokens.. not passwords or anything. At worst they could impersonate you until your token expires.. but you're not a high value target unless you're an admin of an instance.
I used Firefox... So I definitely reset my password. Thing is I do not see an option for Lemmy where you can "sign out everywhere" which is the counter to Auth token stealing.
So I had to change it so that the Auth token would expire. Whilst I am not an admin I won't take the chance. It could compromise other users and I do not want to take that risk.
Apparently the fix for the vulnerability signs everyone out.
lmao I'm so stupid I pressed on that image and now my account is compromised. oh well it forced to create another and this is my first hack yayyyyy!
Clicking the image isn't the issue, scrolling by it will nab your Auth tokens. Resetting your password will reset the Auth tokens protecting your account. A sign out everywhere button would fix it but that isn't an option yet. It really needs to be.
There's so many things wrong with this I don't even know where to start
Wtf how is this even possible? Are the Lemmy devs smoking crack? If you're going to run a reddit alternative, it may be wise to sanitize the fuck out of everything posted on there.
Please feel free to perform a full security audit.
You are free to open a PR
Not really helpful though is it? It's like going to a friend's house and asking why there is a sink hole in the middle of the floor that everyone is walking around, and they say "feel free get a hammer out".
the threadiverse wasnβt exactly popular until the reddit exodus
id probably flip it: are lemmy users smoking crack? if youβre going to run to a reddit alternative, itβd be wise not to choose alpha software!
Little Bobby Tables strikes again
Now seriously, people forget that Lemmy is alpha software, and Kbin is even younger
well Reddit was hacked so lemmy is still on track
Β―_(γ)_/Β― Lemmy.
Swear this is the same guy that did the trending community spam a few days ago, he was angry about being banned for squatting on known subreddit names here on Lemmy, even the compromised admin account said something about it in her comments before this happened π€¦ββοΈ
Wait, was that the one that had a community list well into the twenties? Or was that someone else? I don't think all that stuff reached me, but I did hear about a wannabe powermod like a week and a half ago. Much good that does anyone in a defederated system.
His username at the time was βLMAOβ and I think soβ¦ he did it again on another Lemmy instance but used a different username that time as well π
Deeply unfortunate that something like this could happen, you always hope that code injection vulnerabilities are found before someone is hacked. With that in mind, this shows the importance of two security principles: always parse and clean user input and don't click links (including images) before checking where they are going to send you.
This used an onLoad which isn't generally shown when you hover over a link in a browser. Most people, even devs, aren't going to jump on the console to check every link.
NoScript would probably have helped though.
What kind of terrible markdown editor allows adding onload scripts to images though.. it's insane.
Also doesn't help when using mobile and there's no hover over
You can usually click and hold on mobile and an popup will appear showing the link (I think) - or you can click and hold and copy the link and paste it somewhere to see where it's going to go.
Yeah good luck.
You can, yes, but it's not the sort of thing most do before taping. The hover-over is passive.
Script kiddies. insert eyeroll emoji here
Here take this: π
Deeply unfortunate that something like this could happen, you always hope that code injection vulnerabilities are found before someone is hacked. With that in mind, this shows the importance of two security principles: always parse and clean user input and don't click links (including images) before checking where they are going to send you.
Itβs worse than that. Until Lemmy is more mature, I would reccomend using the lite version of Lemmy, the JS-free version, for sake of client side security. Alternatively, or as an added point of security, the front-ends themselves should implement more sanitazion themselves. Iβm willing to spend some free time vulnerability testing, but I would need a dedicated sand-box for that.
The ansible method of setting up a lemmy instance generally "just works". I set one up for federation tests with kbin recently.
When I wanted to do some lemmying earlier, the LemmyWorld logo said 'Israel', and when I put my cursor over it, it said 'N***a Style. Then when I clicked the logo (stupid me, no doubt), it redirected me to a pic of some dude with a cigar, with the caption (iirc) "I r * pe kids in the woods". I did a virus scan which came up clear. Dunno what else to do when shit like that happens, as I am not the brightest bulb in the chandelier.
I have not seen any notice as to how either users or admins should mitigate the problem so far. Obviously, admins should update once a new release is out, but beyond that...
From an end-user standpoint, I would guess -- I have not looked at the code and have not been working on the security hole -- the following:
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This basically allows the attacker to masquerade as a currently-logged-in user who has viewed their link.
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Viewing content on a lemmy server while logged in as an admin right now is probably a particularly bad idea.
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I don't know what the full impact is for a regular user account, but it's probably possible for at minimum posts to be deleted, and posts to be made as someone. In kbin, my account shows my email address, so if lemmy does the same, it would be possible to link an email account used for registration with a username. If you used a throw-away email account that is publicly-accessible -- as I did -- that could allow for full account compromise.
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Viewing content while not logged in is probably safe -- maybe they can make Javascript run from a link, but without you being logged in, there isn't anything interesting that the attacker can do. If I were going to be viewing content on lemmy servers right now, and okay with being limited to lurking, I might do that for a few days until the issue is resolved and lemmy servers update.
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I don't know if kbin is vulnerable. It didn't accept the URL given in the bug as an example of a malicious URL when I tested submitting one, but it's possible that it trusts URLs coming from federated servers, which I did not check.
https://github.com/LemmyNet/lemmy-ui/issues/1895#issuecomment-1628270766
As for a user, I'd avoid using any Lemmy instances from the browser until they get updated.
beehaw isn't down, just very slow, which is it's normal state of being if we're being honest
I don't see any weird content, but I couldn't log in. There's a notification at the bottom that says "logged in" but I'm still blinded by light mode.
In all seriousness, no one is talking about this, but this is the one disadvantage of open source software being developed by volunteers, we don't know exactly how the admin accounts were hacked but the XSS stuff is really basic stuff, none of those fields were sanatised at all, and it makes me concerned what else has been missed, obviously the advantage of open source is in time this stuff can get fixed, but this is what happens when loads of people who aren't experts contribute to a site.
In comparison to sites where there is a fully hired developer team the quality of the code is significantly better. I really hope the passwords were hashed on these instances and the hackers didn't get plain text passwords or anything really bad like this.
One thing and credit to Ernest, as I've contributed there he does very thorough code reviews and his quality of code is very good, its why im confident kbin won't be hacked.
I think you've never worked in software, or even used software, if you think paid close source apps don't have issues like this. They can be worse because they're written by interns and no one there actually cares, they just want their paycheck
yes and no: there are a couple of schools of thought!
of course, code by a lot of people without proper review is⦠risky
however, at least itβs able to be reviewed! and in time and with enough eyeballs, hopefully that code will become far more robust. thatβs the benefit of transparency: anyone can review any line at any time!
remember: closed-source code as plenty of vulnerabilities too! just if we canβt review it, itβs much harder to work out what they might beβ¦ often, closed source vulnerabilities can exist for years without the vendor ever patching them because nobody is calling them out on itβ¦ hell, they can even know that their software is actively being exploited and justβ¦ not tell anyone
view more: next βΊ