  The ability of an eavesdropper to compromise the security of a quantum
communication system by changing the angle of the incoming light is well-known.
Randomizing the role of the detectors has been proposed to be an efficient
countermeasure to this type of attack. Here we show that the proposed
countermeasure can be bypassed if the attack is generalized by including more
attack variables. Using the experimental data from existing literature, we show
how randomization effectively prevents the initial attack but fails to do so
when Eve generalizes her attack strategy. Our result and methodology could be
used to security-certify a free-space quantum communication receiver against
all types of detector-efficiency-mismatch type attacks.
