BIND: Denial of service

Background

ISC BIND is the Internet Systems Consortium implementation of the Domain Name System (DNS) protocol.

Description

Matthias Urlichs reported that the dns_db_findrdataset() function fails when the prerequisite section of the dynamic update message contains a record of type “ANY” and where at least one RRset for this FQDN exists on the server.

Impact

A remote unauthenticated attacker could send a specially crafted dynamic update message to the BIND daemon (named), leading to a Denial of Service (daemon crash). This vulnerability affects all primary (master) servers – it is not limited to those that are configured to allow dynamic updates.

Workaround

Configure a firewall that performs Deep Packet Inspection to prevent nsupdate messages from reaching named. Alternatively, expose only secondary (slave) servers to untrusted networks.

Resolution

All BIND users should upgrade to the latest version:

 # emerge --sync
 # emerge --ask --oneshot --verbose ">=net-dns/bind-9.4.3_p3"