As far as I know, pkexec doesn't validate arguments, so it might not be ideal if you are worried about people trying to trick it.
Sometimes, I use a sudo command with -s options for keeping
environment variables for users account(sudoer). I also know -s option
runs the shell specified by the SHELL environment variable. But the
SHELL environment variable can be manipulated by other users having
the same privilege.
So, I think an adversary is able to abuse the changing SHELL
environment variable for privilege escalation like a video below. (I
assume the adversary owned the permission for executing a shell on a
remote)
https://youtu.be/JSQjIm7377o (unlisted state)
I know it is uncertain when the sudo is executed with -s option by sudoer.
Anyway, I have thought of the solutions to the issue below.
- using a pkexec of a Policy kit,
- disable a ptrace function via kernel.yama.ptrace_scope, CAP_SYS_PTRACE.
Could you give some advice and comments?
Thx.