In this paper, the authors conduct an analysis of the previously over-looked attack surface related to DNS, and are able to uncover even stronger side channels that have existed for over a decade in Linux kernels. The side channels affect not only Linux but also a wide range of DNS software running on top of it, including BIND, Unbound and dns-masq. They also discovered that about 38% of open resolvers (by frontend IPs) and 14% (by backend IPs) are vulnerable including the popular DNS services such as OpenDNS and Quad9.
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