ISC BIND Denial of Service (Jun 30, 2011)

BIND is by far the most widely used DNS software on the Internet. It provides a platform that is fully compliant with published DNS standards.

The Domain Name System Security Extensions (DNSSEC) is a set of extensions to DNS which provide to DNS clients origin authentication of DNS data, authenticated denial of existence, and data integrity. Several DNS record types were created or adapted to use with DNSSEC:

  • DS
  • NSEC
  • NSEC3

A vulnerability exists in the BIND’s implementation of RRSIG handler. An attacker can host a DNS server which sends malicious RRSIG records to other DNS servers. Successful exploitation would terminate the “named” (the BIND name server process) on the vulnerable DNS servers.

The vulnerability has been assigned as CVE-2011-1910.

SonicWALL has released an IPS signature to detect and block known exploits targeting this vulnerability. The following signature was released to address this issue:

  • 6790 – ISC BIND RRSIG RRsets DoS