  A coordinated cyber-attack on grid meter readings and breaker statuses can
lead to incorrect state estimation that can subsequently destabilize the grid.
This paper studies cyber-attacks by an adversary that changes breaker statuses
on transmission lines to affect the estimation of the grid topology. The
adversary, however, is incapable of changing the value of any meter data and
can only block recorded measurements on certain lines from being transmitted to
the control center. The proposed framework, with limited resource requirements
as compared to standard data attacks, thus extends the scope of cyber-attacks
to grids secure from meter corruption. We discuss necessary and sufficient
conditions for feasible attacks using a novel graph-coloring based analysis and
show that an optimal attack requires breaker status change at only ONE
transmission line. The potency of our attack regime is demonstrated through
simulations on IEEE test cases.
