It depended on having some malware installed in the system. If they were able to get some malware on the target system then why use such a convoluted method to get the data?
Some years back there was a more plausible method of getting the data. It had to do with receiving and interpreting the RF signals produced by the system. No malware needed; only a very sensitive receiver. I believe this is also the basis for the conspiracy theorists using faraday cages for their systems.