Screen Locker (In)Security - Can we disable these at least 4 backdoors?

[Patrick]

@Patrick

Backdoor #4: Ctrl-Alt-KP_Multiply .

Does not do anything for me. Seems disabled. Could you please confirm that it does not do anything for you too?

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=347803 say this is obsolete. Cannot find this option in man page xorg.conf(5) — xserver-xorg-core — Debian buster — Debian Manpages anymore.

Seems removed from upstream X. Only mentions are in archived man pages.

site:https://www.x.org AllowClosedownGrabs

@Patrick

Backdoor #3: Alt-SysRq-F .

This is the Linux kernel “OOM-killer” keystroke. It shoots down random long-running programs of its choosing, and so might might target and kill xscreensaver, and there’s no way for xscreensaver to protect itself from that. You can disable it globally with: sudo ‘echo 176 > /proc/sys/kernel/sysrq’

(As of version 5.41, if xscreensaver is setuid, and you are running Linux 2.6.37 or newer, xscreensaver attempts to request that the kernel’s out-of-memory assassin not randomly unlock the screen on you, but it’s only a request.)

SysRq should be sufficiently tamed already. Separate forum thread:

SysRq (Magic SysRq key)

Is SysRq tamed enough currently? Is SysRq tamed enough currently? Security discussion summary: System Recovery using SysRq Key If not, please summarize/bump here: SysRq (Magic SysRq key)