Wired looks
at the security issues stemming from the complexity of the Bluetooth
standard.
“Bluetooth has certainly been investigated to a degree, but
researchers say that the lack of intense scrutiny historically stems again
from just how involved it is to even read the standard, much less
understand how it works and all the possible implementations. On the plus
side, this has created a sort of security through obscurity, in which
attackers have also found it easier to develop attacks against other
protocols and systems rather than taking the time to work out how to mess
with Bluetooth.“

Source: LWN.net – Bluetooth’s Complexity Has Become a Security Risk (Wired)