I recently got asked a question that I ‘m sure I had the right answer.
What if someone changed the permissions of /bin/chmod and removed the execute bits?
-r–r–r–. 1 root root 52472 Oct 15 2014 /bin/chmod
You cant ‘execute’ /bin/chmod because the execute bit is no longer set. I immediately thought. OK.. Reinstall the RPM (rpm -qf /bin/chmod – coreutils package) or copy the chmod bin from another host.
Well it turns out that in perl you can use the ‘chmod’ call from a ‘one-liner’ to set the permissions. As root.
perl -e ‘chmod 0755, “/bin/chmod”‘
-rwxr-xr-x. 1 root root 52472 Oct 15 2014 /bin/chmod
Guess I need to learn more about the system calls themselves instead of just executing binaries.