The Cisco OpenDNS service was susceptible to a DNS pulsing attack due to improper handling if a large volume of queued DNS requests was received. This attack takes advantage of multiple commonly implemented DNS mechanisms. DNS queries are sent at a low rate and amplified into large-sized responses. This concentrates the DNS responses into a short, high-volume burst to overwhelm target systems.
Security Impact Rating: Informational
Source:: Cisco Security Advisories