>You wifi cards constantly sends out “hey home network, are you there? Hey network of my mate, are you there?” for every network you where connected at one time, resulting in a pretty unique used AP list that leaks astonishing metadata like where you where on vacation in some scenarios (“trump hotel guest wifi”) and so on… More a threat to smartphones, but of course also applies to laptops.
IIRC this only applies if you have connected to "hidden" networks. Directed probes (ie. probes with SSIDs) are only really needed in those cases because the SSID isn't being broadcasted. For networks with SSIDs clients will send a probe without any APs, which causes all nearby APs to reply.
I believe mobile devices use active scanning instead of passive because it reduces battery usage. It reduces battery usage because it means the wifi radio does not need to be listening constantly for beacon frames.
Célestin Matte. Wi-Fi tracking : Fingerprinting attacks and counter-measures. Networking and Internet Architecture [cs.NI]. Université de Lyon, 2017. English. NNT : 2017LYSEI114. tel-01921596f
2 comments
[ 3.3 ms ] story [ 12.2 ms ] threadIIRC this only applies if you have connected to "hidden" networks. Directed probes (ie. probes with SSIDs) are only really needed in those cases because the SSID isn't being broadcasted. For networks with SSIDs clients will send a probe without any APs, which causes all nearby APs to reply.
Célestin Matte. Wi-Fi tracking : Fingerprinting attacks and counter-measures. Networking and Internet Architecture [cs.NI]. Université de Lyon, 2017. English. NNT : 2017LYSEI114. tel-01921596f
Page 24: https://tel.archives-ouvertes.fr/tel-01921596/document