xz-mirror VS systemd

A mirror is here[1] for someone who wants to read the commit messages, though as I understand it is insufficient for reproducing the backdoor at compile time because it is missing the m4/ files required for this purpose.

[1] https://github.com/supriyo-biswas/xz-mirror

It isn't cleaned up at boot IIRC. Unless you leave your computer off for 30 days and then come back [1] :).

But it shouldn't be too hard to write a relativly simple systemd.unit file that does that at boot. After all the main part would be `Requires/After=local-fs.target` and something like `ExecStart=bash -c 'rm -rf /var/tmp/*'` I think (you'd need to double check what exactly to do if you want to do this).

[1] https://github.com/systemd/systemd/issues/33162

Email: v[at]vda.io

Hi HN! I'm a Linux security engineer looking for work on Open Source software. I've done some security work in the Linux Kernel (containerization primitives), in systemd as well as some work on Secure Boot.

Notably I've implemented auto-enrollment of secure boot keys in systemd. See (https://github.com/systemd/systemd/pull/20255 & https://lpc.events/event/16/contributions/1259/).

Lately, I've been very interested in MicroVMs and minimizing the Linux Kernel attack surface.

Message me if any of that sounds interesting!

No, the OP was not sent any harassment, the OP _did_ the harassment as it can be seen in the tweets. I mean, they are right there, just click on the links you shared. One of the OP's followers even openly called for the assassination of the project maintainer, and you have the galls to defend him? This is truly deranged stuff.

And again, there is no "vulnerability", there is simply a person that doesn't know how Linux works and has learned something new. Which again it's fine, nobody knows everything and we all learn new things everyday, it's just that normal and sensible people don't use that to make grand claims on social media and start harassment campaigns culminating in death threats.

Professional security researchers responsibly report real issues using the appropriate channels, such as defined at: https://github.com/systemd/systemd/security/policy this is not the work of a researcher, this is a grifter looking for self-promotion on social media.

> 3. even `adduser` will not allow it by default

5. useradd does allow it (as noted in a comment). 6. Local users are not the only source, there things like LDAP and AD.

7. POSIX allows it:

* https://github.com/systemd/systemd/issues/6237#issuecomment-...

> I for one love to type out 13 extra characters

FWIW, systemd is normally pretty good at providing autocomplete suggestions, so even if you don't want to set up an alias you'll probably just have to type `--b ` to set it.

> I wonder what random ASCII escape sequences we can send.

According to the man page source[0]:

> The color specified should be an ANSI X3.64 SGR background color, i.e. strings such as `40`, `41`, …, `47`, `48;2;…`, `48;5;…`

and a link to the relevant Wikipedia page[1]. Given systemd's generally decent track record wrt defects and security issues, and the simplicity of valid colour values, I expect there's a fairly robust parameter verifier in there.

In fact, given the focus on starting the elevated command in a highly controlled environment, I'd expect the colour codes to be output to the originating terminal, not forwarded to the secure pty. That way, the only thing malformed escapes can affect is your own process, which you already have full control over anyway.

(Happy to be shown if that's a mistaken expectation though.)

[0] https://github.com/systemd/systemd/blob/main/man/run0.xml

[1] https://en.wikipedia.org/wiki/ANSI_escape_code#SGR_(Select_G...

bash & zsh are supported by upstream: https://github.com/systemd/systemd/tree/main/shell-completio...