New BIND Vulnerabilities Threaten DNS Availability

One of the most common pieces of software for implementing a Domain Name System (DNS) server — BIND — has just become the subject of security advisories from the Internet Systems Consortium and a related notice from DHS.

The advisories cite two new vulnerabilities in BIND. Both describe a scenario in which one of the components of BIND, rbtdb.c, can be driven to a failure state and effective denial-of-service for name resolution. In one vulnerability, rapidly changing zones can lead to a miscount of the zones with a resulting failure of the component. 

In the other vulnerability, a poor implementation of a feature known as serve-stale can lead to a similar failure, with identical results — no access to domain name resolution.

Neither of the vulnerabilities have been exploited in the wild and only specific versions of BIND are susceptible. All organizations running BIND are urged to read the CVEs to determine whether they are at risk and should begin remediation. 

For more, read here, here, and here.