Date: 2021oct18 OS: Linux Keywords: cron Q. Linux: Deny all crontab access A. As root make a file called

/etc/cron.allow

With content:

# Nobody is allowed

Since this file is a list of the allowed users and its empty that means that nobody is allowed. The comment isn't necessary -- it just to remind future you what's going on. Of course, later, you can add selected users or delete the file as needed. I had an exploit which added a cron job as user apache so that's why I did this. More info https://linux.die.net/man/1/crontab