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by labelbabyjunior 71 days ago
A local privilege escalation to root via an exploitable service?

Doesn't Linux have one of these CVEs...each week?

4 comments

Only if you’re running daemons as root. Which would be an idiotic move to begin with because that’s not how distros package their services. So you’d have to intentionally make this mistake.
Intentionally?

Ignorance is bliss! Simply use docker in its (old) default setup, instead of podman, apptainer, docker-rootless ... and that world is yours.

Added bonuses are the incredible stupid integration with ufw on Ubuntu, images with laughable uid mapping, ...

How that shit got traction baffles me.

That’s just the docker daemon. The actual docker services would (or at least should) still be running as its own user/group just like they would if you were running them on the host.

And that’s exactly how any reputable image would be built.

Probably, but is that service deployed as part of the base operating system or a third party package? Can you remove the service if you deem the crazy service behaviour is unnecessary or too risky for your usecase?
Not quite every week, but yeah it has a lot. And if the target uses sudo at all you don't even need an exploit!

But nobody mentioned Linux. There's no need for whataboutism. They both shouldn't have these vulnerabilities.

> And if the target uses sudo at all you don't even need an exploit!

Why would a target executable use sudo? There are proper mechanisms for automated elevation of permissions and sudo isn’t it.

sudo is designed for user interactivity. And by default prompts for a password. However some people get lazy and disable the password entry requirement.

A target user. If you get local code execution on the account of a user that uses sudo you can trivially got root. Doesn't matter if they disabled the password authentication or not.
Of course it matters if they disabled password authentication. If you require password authentication when running sudo then an attacker has to find a RCE exploit and then crack a password. Which is waaay beyond any effort the average attacker is willing to invest. Because At that point, root access isn’t really worth the effort.

An attacker will probably just use the host for sending spam emails, bot / DDoS traffic or look for other daemons they can jump to which weren’t web accessible (eg a database).

And furthermore, if you’ve got a RCE in a daemon then that code is the running as the daemons’ user. Which shouldn’t be in the sudoers file (eg wheel group) to begin with.

> If you require password authentication when running sudo then an attacker has to find a RCE exploit and then crack a password.

Nope! Just alias sudo to something that logs the password.

Interesting. If that’s possible (I haven’t tested it, but I’m sure it is) then you wouldn’t even need to log the password. You could just alias sudo to a bash script that runs your malicious payload using the real sudo. Then the user would run the command, be prompted for their password by the real sudo, and be none the wiser that a malicious script has just been executed

For what it’s worth, Windows’ security model says it’s not an exploit that programs can grant themselves admin rights if the user is an admin (https://github.com/hfiref0x/UACME). But afaik Linux doesn’t have that model so it is a bit of an issue that this is possible

How are you going to do that without write access to the users home directory?

Like I said before, your RCE exploit will be running as the user and group of the service you exploited. For example www:www

So you’re not going to be able to write into Joe Bloggs .bashrc file unless Joe was stupid enough to enable write permission to “other”. Which, once again, requires the user to purposely modify the system into being less secure than its default configuration

No.