Systems, methods, and devices of the various aspects enable detecting anomalous electromagnetic (EM) emissions from among a plurality of electronic devices. A device processor may receive EM emissions of a plurality of electronic devices, wherein the receiving device has no previous information about any of the plurality of electronic devices. The device processor may cross-correlate the EM emissions of the plurality of electronic devices over time. The device processor may identify a difference of the cross-correlated EM emissions from earlier cross-correlated EM emissions. The device processor may determine that the difference of the cross-correlated EM emissions from the earlier cross-correlated EM emissions indicates an anomaly in one or more of the plurality of electronic devices.