this post was submitted on 29 Jun 2023
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Found the error Not allowed to load local resource: file:///etc/passwd while looking at infosec.pub's communities page. There's a community called "ignore me" that adds a few image tags trying to steal your passwd file.

You have to be extremely poorly configured for this to work, but the red flags you see should keep you on your toes for the red flags you don't.

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[–] Rooster@infosec.pub 13 points 1 year ago

If you find something, report it. Don't experiment on the public.

https://www.bugcrowd.com/resources/guide/what-is-responsible-disclosure/

[–] himazawa@infosec.pub 11 points 1 year ago* (last edited 1 year ago) (1 children)

Is this, by any chance, originated from the sub called ignore me? In that case is probably my bad because is set as the image of the channel. I was playing with lemmy in the previous version and forgot about it, sorry.

It will not work since your browser can't access local file that easily without breaking the sandbox :) also the that alert appears because your browser is trying to load an image with that path, nothing dangerous or remotely exploitable, don't worry.

Edit: I removed it so you shouldn't see the alert anymore.

P.S. not, it's not trying to steal anything, it's your browser trying to load that file as an image but instead of being let's say this url: https://beehaw.org/pictrs/image/c0e83ceb-b7e5-41b4-9b76-bfd152dd8d00.png (this sub icon) , it's this one file:///etc/passwd so you browser is doing the request to your own file. Don't worry, nothing got compromised.

/cc @shellsharks@infosec.pub

[–] BlueBockser@programming.dev 1 points 1 year ago (1 children)

But... why? Why even put that URL there? Even if it was most likely harmless for all users, this still looks like an attempt at data exfiltration.

[–] himazawa@infosec.pub 1 points 1 year ago

Because I wanted to try if others URI schemas were supported instead of http / https. file:// was a valid one. Don't worry, the day an attempt of data exfil will happen, you will not see it though your console logs.

[–] farthom@lemmy.ca 7 points 1 year ago (1 children)

Holy shit this is kind of unsettling. Though I would expect ALL major browsers to reject reading any local files like this..... would this kind of thing actually succeed somewhere/somehow?

[–] Rooster@infosec.pub 4 points 1 year ago (3 children)

If you ran your browser as root and configured your browser to load local resources on non-local domains maybe. I think you can do that in chrome://flags but you have to explicitly list the domains allowed to do it.

I'm hoping this is just a bad joke.

[–] skullgiver@popplesburger.hilciferous.nl 1 points 1 year ago* (last edited 9 months ago)

[This comment has been deleted by an automated system]

[–] fox@vlemmy.net 1 points 1 year ago (2 children)

you don't need to be root to read /etc/passwd

[–] trachemys@iusearchlinux.fyi 4 points 1 year ago

That’s because passwd doesn’t store the password hashes. Just user names.

[–] Greg@lemmy.ca 3 points 1 year ago* (last edited 1 year ago) (1 children)

Are you sure? What do you get when you run $ cat /etc/passwd in terminal? Just paste the results here 😇

Edit: to anyone reading this on the future, don't actually do this, it was a joke

[–] fox@vlemmy.net 6 points 1 year ago

yup pretty sure

$ cat /etc/passwd
fox:hunter2:1000:1000::/home/fox:/usr/bin/zsh

😉

[–] farthom@lemmy.ca 0 points 1 year ago (1 children)

Yeah, seems highly unlikely to ever yield any results. Even if you did manage to read a file, you have to get lucky finding a password hash in a rainbow table or the password being shit enough to crack.

[–] nzodd@beehaw.org 1 points 1 year ago

Also generally the actual password (or rather its hash) is stored in /etc/shadow on most systems from the past 20 odd years.

[–] laenurd@lemmy.lemist.de 0 points 1 year ago

While this is concerning, I wonder what the author(s) of this were thinking would happen. I assume it's supposed to be an attempt at stealing the server's passwords, since I at least know of no browser that freely allows access to local files.