I made the following demo for a customer in the scope of a security awareness event. When speaking to non-technical people, it's always difficult to demonstrate how easily attackers can abuse of their devices and data. If successfully popping up a "calc.exe" with an exploit makes a room full of security people crazy, it's not the case for "users". It is mandatory to demonstrate something that will ring a bell in their mind.

As people want to be constantly online, they (ab)use of wireless access points. By default, connected devices keep a history of all used wireless networks and constantly try to find them again. The idea of the demo is simple:

1. Collect all the SSID's broadcasted by mobile devices present in the audience
2. Geolocate the SSID's using the Wigle API
3. Display them on a map

[Note: For privacy reason, this demo must be performed with the authorization of people in the audience]

First, collect SSID's using tshark and a Wireless network card that can be switch into monitoring mode:

# iwconfig $interface mode monitor
# ifconfig $interface up
# tshark -i $interface -n -l subtype probereq | tee -a /tmp/ssids.tmp
Feb   7 18:37:39 Probe Request from 08:ee:8b:xx:xx:xx for SSID 'xxxx Airport'
Feb   7 18:36:54 20:a2:e4:xx:xx:xx trying to associate with 'Free Wireless'
Feb   7 18:36:49 Probe Request from 20:a2:e4:xx:x:xx for SSID 'Free Wireless'
Feb   7 18:36:25 Probe Request from 58:40:4e:xx:xx:xx for SSID 'Free Wireless'
Feb   7 18:36:22 Probe Request from 0c:e7:25:xx:xx:xx for SSID 'Free'
Feb   7 18:36:12 Probe Request from e8:50:8b:xx:xx:xx for SSID 'xxxxx-wifi'
Feb   7 18:36:04 f0:25:b7:xx:xx:xx trying to associate with 'Airport_Free_xxxxxx'
Feb   7 18:36:04 Probe Request from f0:25:b7:xx:xx:xx for SSID 'Airport_Free_WiFi_xxxxxx'
Feb   7 18:35:46 64:9a:be:xx:xx:xx trying to associate with 'swisscom'
Feb   7 18:35:46 Probe Request from 64:9a:be:xx:xx:xx for SSID 'swisscom'
Feb   7 18:35:40 Probe Request from 24:77:03:xx:xx:xx for SSID 'UM'
Feb   7 18:35:38 Probe Request from 24:77:03:xx:xx:xx for SSID 'UM'
Feb   7 18:35:34 Probe Request from 20:a9:9b:xx:xx:xx for SSID 'xxxxx'
Feb   7 18:35:31 Probe Request from 20:a2:e4:xx:xx:xx for SSID 'Free Wireless'
Feb   7 18:35:15 Probe Request from 8c:00:6d:xx:xx:xx for SSID 'xxxxNET'
Feb   7 18:35:15 Probe Request from 80:ea:96:xx:xx:xx for SSID 'Airport_Free_WiFi'
Feb   7 18:35:10 38:ca:da:xx:xx:xx trying to associate with 'xxxxNET'

Let tshark collect SSID's for a few minutes (the list will quickly grow). The next step is to use the Wigle[1] API to get geolocation data. 

[Note: The free API allows only a limited number of queries per day]

I wrote a Python script[2] which queries the API and generates a CSV file:

# grep SSID /tmp/ssids.tmp | awk -F "'" '{ print $(NF-1) }'| sort -u >wigle.data
# python wigle.py
# head wigle.csv
SSID,Lat,Lon
AIRPORT FREE WIFI,50.88093567,7.11556339
AIRPORT FREE WIFI,28.45140457,-13.8698101
AIRPORT FREE WIFI,43.30202866,-8.38176537
xxxxxxxxxxx,43.52931595,5.45100164
xxxxxxxxxxx,36.88293457,10.33142185
xxxxxxxxxxx,48.85987091,2.22434855
xxxxx,40.48699951,-3.58421397
Airport_Free_WiFi,-6.86642265,39.20762634
Airport_Free_WiFi,52.30990219,4.76001358

The last step is to map those coordinates on a world map. Splunk does this with just one query:

| inputcsv wigle.csv | stats count by SSID, Lat, Lon | geostats  latfield=Lat longfield=Lon count by SSID

A zoom on the map may reveal nice locations where your victim could have spent some fun times:

What about the accuracy of those maps? It relies on the Wigle database which is populated by volunteers. Generic SSID's like "Free Wifi" or "Guest" won't give good results but a unique hotel name will make it perfectly. It is not possible to put the broadcasted SSID's on a timeline to track the moves in the past but it's easy to spot two people who met or visited the same place in the past.

Given that people keep their phone default name ("iPhone of John Doe"), this demo generates always a little stress when you ask the victim: "So, Mr Doe, How was your stay at the hotel La Playa?".

[1] https://wigle.net/index
[2] https://github.com/xme/toolbox/blob/master/wigle.py

Xavier Mertens (@xme)
ISC Handler - Freelance Security Consultant
PGP Key