> perhaps i misunderstand it, though must 'resonance'
     > be audibly acoustic, and would a SCIF actually defend
     > against "vibrations" at all frequencies.

   the question highlights how ill-suited the 'spy agencies'​​ are for
   conducting asymmetric anything.
   Unless they had a Brain inside think of a mechanism and explain it to
   an Engineer to propose to a Facilities Security Manager who obtained
   confirmation from a Director, they would be vulnerable.
   For instance, TEMPEST security - every SCIF has it because inside it
   was well documented/implemented.  SEISMIC security - no SCIF*** is
   isolated from seismic vibrations modulated with data.  So, to
   ex-filtrate data, have those passing circus elephants stomp their feet
   in predetermined patterns.  Or make one of those "Dune" style thumpers.
    The worms in this case being .... ?
   *** I'm suppose some very few SCIFs are vibration isolated for various
   reasons, but not as an exfil channel.
   -daniel