Don't hack the hackers

Sometimes you need to be extremely careful what you are hacking into, take the following hypothetical situation:

Walking through town, I was keeping one eye on my frequency counter as I quite often do.  Passing through the main shopping street I spotted a transmission in the 1.5Ghz band, it’s hard to be exact with my cheap frequency counter.  Interested, I wandered around trying to find the source and discovered it was strongest on one side of the street between a phone shop and a bank.  So I stood around for a while, waiting to see if I could eek out the source or see any likely candidate.

It’s then that I spotted the bank’s cash machine, and vaguely wandering towards it the signal got stronger.  Cash machines aren’t supposed to transmit anything, and it took me longer than it should have to realise that somebody had attached a card reader and wireless camera in order to steal peoples credit card numbers.

I then smoothly put my counter away and started walking, just before two mounted policemen turned round the corner and started to approach the bank…