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More apps and devices seem to be using wireless proximity as some kind of authenticator, along with the assumption that a specific received signal strength conf
by oakwhiz 13y ago
More apps and devices seem to be using wireless proximity as some kind of authenticator, along with the assumption that a specific received signal strength confirms the user's intent to perform some action. However, such systems seem to be quite prone to a simple attack consisting of a battery-powered bidirectional amplifier connected a pair of highly directional antennas. Simply point one antenna toward the user's phone and the other antenna toward the user's computer, and you can fool the computer into thinking the user's phone is closer than it really is.
- lstamour 13y agoThe trick is in opening the app and knocking. The knock releases the advertisement. Similarly, in other use cases, geofencing from the phone means the phone has to think it's nearby to release the signal. Not saying it can't happen, but that's a lot of work. Easier to just hack the device, prompt the user with a fake pin-pad or login screen, or do social engineering and/or gain physical access. By the way, this attack is much more successful in reverse, for listening to and replaying keycard transactions. I was shocked to discover how little materials would be needed to make a decent amplified antenna.