Concise Guide to DNS and BIND, The

chroot and Least Privilege

Software is vulnerable to various attacks that can cause different problems. One of the most insidious is attacks resulting in the attacker gaining root access to your mission-critical servers. BIND has been vulnerable to such attacks, but even so, the impact of such a compromise can be minimized. Not that gaining control of a nameserver isn't useful if you want to break into some network.

The principle of least privilege dictates that you run a service with exactly those access rights it needs, and you restrict its capability of accessing anything else. Although BIND does need to run as root to start, to be capable of listening on port 53, which is privileged, it does need to run as root after the port has been opened. ...