Countermeasures
Typically, this is where we have the most control as security professionals.
When it comes to wireless, do yourself a favor and change the default SSID. In fact, this might be a great opportunity to practice something I always talk about, and that is misdirection. For example, if I have a D-Link router, I know the default SSID is called D-Link. I'll switch it to Linksys or Tsunami, a different manufacturer, because when the attacker is wardriving through my neighborhood or a business environment and he sees D-Link, he'll throw D-Link attacks or vulnerabilities at that device, which obviously won't work.
Disable SSID broadcasting
Again, this will not stop an attacker, but that's not your job because that job is impossible. Your job is to slow them down. The attacker dared to be looking for a hidden SSID.
Disable remote login and wireless administration to the device
The last thing you want is for the attacker to be able to gain...