Using the Domain Name System for System Break-ins

The DARPA Internet uses the Domain Name System (DNS), a distributed database, to map host names to network addresses, and vice-versa. Using a vulnerability first noticed by P.V. Mockapetris, we demonstrate how the DNS can be abused to subvert system security. We also show what tools are useful to the attacker. Possible defenses against this attack, including one implemented by Berkeley in response to our reports of this problem, are discussed, and the limitations on their applicability are demonstrated.