crontab permissions


I want to set up a cron job to install the latest SpamAssasin ruleset every day. I don't really know how to do this, so I thought I would start by visiting the cron job applet in cPanel. When I clicked on it, this was at the top of the window:
/usr/bin/crontab permissions are wrong. Please set to 4755
Can someone explain that to me and tell me where and how I can fix my permissions?

I'll start a different thread about the cron job itself.

Thank you,