How can I verify that a file is being execute as root account?

Question

Let's say we have created a file with root account with -rwsr-xr-x script.sh permissions. We have set suid bit on this file so any user who is gonna execute this file, it's gonna be execute by owner of the file which is root. For example let's look at the passwd command:

$ ls -l /usr/bin/passwd
-rwsr-xr-x 1 root root 68208 Apr 16 17:06 /usr/bin/passwd

This command is similar to our file. Any user who executes this command, it's going to be run as root account no matter if the user is root or has sudo privileges.

The question is how can i verify this subject?

To figure this out I'v tried this: if we look at script.sh contents, I'v wrote this simple script:

#!/bin/bash
if [[ $UID -eq 0 ]]
then 
    echo "Running as root"
else
    echo "Not root"
fi

now if I run this script as a regular user, the output will be: Not root

So how can I check if it's running as root?

Please let me know if I have misunderstanding of the concepts. I'm a newbie.

bash script is run by /bin/bash, which is not suid root binary. — Ipor Sircer, Sep 04 '20 at 15:08
I normally do a check like if [ -w /etc/passwd ]... if you can write to that file then you're either root or the whole system can be compromised :-) — Stephen Harris, Sep 04 '20 at 15:17
Don't depend on environment variables ($UID), they're subject to manipulation. Rather, read man id and use id -u to get the UID. — waltinator, Sep 04 '20 at 17:34

score 0 · Answer 1 · answered Sep 04 '20 at 18:48

0

What about trying something like:

if [ $(whoami) = "root" ]

answered Sep 04 '20 at 18:48

VicerExciser

11

How can I verify that a file is being execute as root account?

1 Answers1