NewsSecurity Vulnerabilities

Cisco OpenDNS Pulsing DNS Denial of Service Attack

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.

Cisco has addressed this issue in Cisco OpenDNS, which is cloud based. No user action is required. Customers can determine the current remediation status or software version by using the Help function in the service GUI.

Customers who need additional information are advised to contact the Cisco Technical Assistance Center (TAC) or their contracted maintenance providers.

Jason Davies

I am one of the editors here at I am a UK based technology professional, with an interest in computer security and telecoms.

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