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New Linux udisks flaw lets attackers get root on major Linux distros

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Re: New Linux udisks flaw lets attackers get root on major Linux distros

#111
post #102

Earlier quoted context omitted.

IPC ?

The GP doesn't understand the vulnerability: https://cdn2.qualys.com/2025/06/17/suse15-pam-udisks-lpe.txt Instead of using something standard like environment variables, pam has a special "pam_env" that contains facts about the user session that it apparently trusts. Users can override pam_env settings by writing to hidden file in ~. So, this exploit chain is more accurately described as "yet another example of utili…

Ok yeah, I had actually misread what the vars were.

But it's the same kind of problem as general environment vars - rather than just a name, maybe it needs metadata of where it came from.

To be clear, I'm talking about the unprivileged to allow_active CVE-2025-6018, not the allow_active to root.

Re: New Linux udisks flaw lets attackers get root on major Linux distros

#112
post #82

Another case of environment variables causing LPE. Wonder if we'll ever end up with something more robust for passing details between processes than parsing ambient settings from strings.

NO, this is NOT environment variables.

It's the wrong argument to a tool, but the suid part has nothing to do with environment variables or cleaning the env up.

PLEASE STOP SPREADING FUD.

Re: New Linux udisks flaw lets attackers get root on major Linux distros

#113
post #87
post #54

udisks, not counting its dependencies, has 265,334 LoC. pmount, in contrast, has 19,978 LoC, or >13x less. sudo, another setuid binary with a lot of policy code, has 210 CVEs / 430.150 kLoC = ~0.5 CVE per kLoC. 57.5% of CVEs have a CVSS >= 7, so 0.5 * 0.575 = 0.2875 CVE7/kLoC. As a back-of-envelope estimate, udisks: 0.2875 CVE7/kLoC * 265.334 kLoC = ~76.28 critical CVEs; pmount: 0.2875 CVE7/kLoC * 19.9780 kLoC = ~5.7…

Ubuntu is switching to a Rust implementation of sudo: https://www.phoronix.com/news/Ubuntu-25.10-sudo-rs-Default Repo here: https://github.com/trifectatechfoundation/sudo-rs It's permissively licensed, unfortunately. Wonder why. It's not a library. But it ought to improve security in the long run.

> Some functionality is not supported, such as […] storing config in LDAP using sudoers.ldap, and cvtsudoers.

* https://github.com/trifectatechfoundation/sudo-rs?tab=readme...

Well that makes it useless for $WORK (for now), as we use LDAP as our central policy repo (and more generally our user account store). Will have to wait until (at least) that's implemented before we can even consider it.

> It's permissively licensed, unfortunately. Wonder why.

So it can be used distributed with fewer legal hassles.

Re: New Linux udisks flaw lets attackers get root on major Linux distros

#114
post #2

As someone who has been using linux quite happily on the desktop for more than 20 years now, I have to say it remains an eternal experiment, feature wise as well as security wise.

Let us not pretend other OS are flawless as well. Microsoft is constantly patching and Apple has been the source of so many hacks that thousands of VIPs were affected and a person was murdered.

Re: New Linux udisks flaw lets attackers get root on major Linux distros

#115

Earlier quoted context omitted.

I'm pretty sure, that the BSD family is pretty mature and secure. Linux is just good enough for most people.

>is pretty mature and secure They are still missing something like capability based security like iOS and Android have where apps have to be granted access to use things like files or the camera. It may have been considered secure a couple decades ago, but they have fallen behind the competiton.

iOS so so insecure that thousands of people have been hacked and at least 1 person was killed.

The last place in security is iOS.

Re: New Linux udisks flaw lets attackers get root on major Linux distros

#116
post #102

Earlier quoted context omitted.

IPC ?

The GP doesn't understand the vulnerability: https://cdn2.qualys.com/2025/06/17/suse15-pam-udisks-lpe.txt Instead of using something standard like environment variables, pam has a special "pam_env" that contains facts about the user session that it apparently trusts. Users can override pam_env settings by writing to hidden file in ~. So, this exploit chain is more accurately described as "yet another example of utili…

https://xeiaso.net/talks/surreal-horror-pam-2021-11-09/

Re: New Linux udisks flaw lets attackers get root on major Linux distros

#117
Awww. I was just about to gloat about Slackware avoiding another round of security holes due to its long avoidance of PAM, but it got introduced in 2020. :-(

It looks like some software projects are now entirely reliant upon PAM for authentication and don't support shadow passwords anymore. What a travesty. It's sort of like what happened with Systemd, where so many apps now entirely depend on Systemd, you can't run a Linux desktop without a "fake Systemd" to make things work. (see: Alpine Linux desktop, Slackware desktop)

All of this seems to be due to a kind of creepy crawly takeover of the system components, with new ones designed by enterprise companies and a few highly-opinionated software developers (who work at those companies). They design these components to do a million different things, but they also make them highly coupled and interdependent (which is terrible software design, but standard for enterprise products). This then results in a much more complex system with many more moving parts, and makes breaking it easier.

Since these companies hold sway over the most popular Linux distros with the most users, when they make a radical change, everybody else has to adopt it, just like with the browser world. Powerful incumbents exert an unfair (and unhealthy) amount of influence on our environment.

If you went back to a distro from 20 years ago, there really should only be a couple components: The X ecosystem (kernel drivers, userland drivers, rendering libraries), a console login program, a tty manager, a wifi manager, and, well... i'm struggling to think of anything else you need [after the system has booted]. Kernel drivers used to make up 90% of the hardware interfaces. Originally you just wrote to a device file for things like sound, printing, etc. It was an extremely simple system and it worked very well.

Today you have 80 different daemons all running at the same time in order for the system to work at all. Event buses, policy engines, management frameworks, a couple dozen libraries, and multiple layers of components to do something as simple as run a graphical app in a windowed environment. Is this all necessary? Clearly not, as we did without all this crap 20 years ago. Somebody screwed the pooch on system design.

Luckily, it's Linux, so nobody is forcing us to use all this shit. We can just start over with a new, much simpler system (and try hard as hell to avoid second system effect)

Re: New Linux udisks flaw lets attackers get root on major Linux distros

#118
post #63
post #54

udisks, not counting its dependencies, has 265,334 LoC. pmount, in contrast, has 19,978 LoC, or >13x less. sudo, another setuid binary with a lot of policy code, has 210 CVEs / 430.150 kLoC = ~0.5 CVE per kLoC. 57.5% of CVEs have a CVSS >= 7, so 0.5 * 0.575 = 0.2875 CVE7/kLoC. As a back-of-envelope estimate, udisks: 0.2875 CVE7/kLoC * 265.334 kLoC = ~76.28 critical CVEs; pmount: 0.2875 CVE7/kLoC * 19.9780 kLoC = ~5.7…

It's incredible to me that sudo has that many LoC. I'd assume it would just ask the OS to execute something without restrictions, not have any logic to do so itself.

There is no such API on Linux, it is accomplished by sudo having the setuid bit set, which instructs the kernel to start it as root regardless of the current user. It's probably one of the worst legacy designs still in use - if any binary has setuid set, it runs as root, no questions asked. Conversely, you also have no way of elevating privileges for a running binary. This really should have been solved decades ago with a robust API for authentication and authorisation of running processes to gain and lose privileges, like what Windows has. Having a filesystem bit grant root privileges to a program is insane. There are probably a dozen CVEs waiting to be discovered with silently corrupting the filesystem and setting that bit on your binary.

Re: New Linux udisks flaw lets attackers get root on major Linux distros

#119

Earlier quoted context omitted.

I'm pretty sure, that the BSD family is pretty mature and secure. Linux is just good enough for most people.

A big part of the difference is that the BSDs are designed by a governing committee. They usually don't have 15 different solutions for the same problem, but instead 2-3 solutions that work well. Take filesystems, the official filesystems are UFS(1/2) and ZFS. They have GEOM as LVM and LUKS and more. That being said, the majority of money and development goes into Linux, which by itself may make it a better system (e…

> A big part of the difference is that the BSDs are designed by a governing committee

While I cannot agree nor disagree on the quality of BSDs (haven't used one in 20 years), I find it funny that in this case a design by committee is proof of quality.

I guess it's better than design by headless chicken which is how the Linux user-space is developed. Personally, I am a big fan of design by dictatorship, where one guy at the top either has a vision or can reject silly features and ideas with strong-enough words (Torvalds, Jobs, etc.) - this is the only way to create a cohesive experience, and honestly if it works for the kernel, there's no reason it shouldn't work in userspace.

Re: New Linux udisks flaw lets attackers get root on major Linux distros

#120
post #73
post #63

Earlier quoted context omitted.

It's incredible to me that sudo has that many LoC. I'd assume it would just ask the OS to execute something without restrictions, not have any logic to do so itself.

OpenDoas, a portable version of OpenBSD's doas, has 4260 LoC while doing most you'd expect. Sudo just has a lot of policy tools that most don't even know about, but add to its surface area.

OpenDoas is used by default by Alpine linux for example.
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