Quote:A weakness named NetCAT (Network Cache ATtack) affects all Intel server-grade processors since 2012 and allows sniffing sensitive details by mounting a side-channel attack over the network.
Researchers from the VUSec group at Vrije Universiteit Amsterdam discovered that information present in the CPU cache on systems with Intel’s Data Direct I/O (DDIO) feature enabled.
 
DDIO is specific to Intel server-grade processors and is turned on by default on Intel Xeon E5, E7 and SP families from 2012 onwards.
Its purpose is to share the CPU cache with network devices and peripherals for better performance of server applications in fast networks.
NetCAT is a network-based attack that can be deployed to infer data in the CPU's last-level cache of a remote machine. VUSec researchers showed that an attacker controlling a machine on the network can use this method to infer confidential data from an SSH session without malicious software running on the target system.