Here's an article from back in 2009 that rings a bell: http://news.bbc.co.uk/2/hi/technology/8147534.stm http://news.bbc.co.uk/2/hi/technology/8147534.stm Bas

Here's an article from back in 2009 that rings a bell: http://news.bbc.co.uk/2/hi/technology/8147534.stm http://news.bbc.co.uk/2/hi/technology/8147534.stm Basically, the shared ground of the local electrical infrastructure of any given building may act as an antenna, and allow attackers to detect EM keystroke signals that can be detected on the power plug. They demonstrated it working over distances of 1, 5, 10 and 15m from a target, far enough to suggest it could work in a hotel or office. I think this is the doc from presentation: http://www.blackhat.com/presentations/bh-usa-09/BARISANI/BHUSA09-Barisani-Keystrokes-SLIDES.pdf http://www.blackhat.com/presentations/bh-usa-09/BARISANI/BHU... Sounds like the technique is similar for fax machines.