In this paper we have proposed an approach for vulnerability analysis of a class of cyber-physical reconfiguration attacks called coordinated variable structure switching. In such an attack, an opponent who gains control over a target circuit breaker, relay or switch can apply a given switching sequence to destabilize the system even if the system is stable in static switch positions. Our analysis approach is illustrated through a case study of the Western Electricity Coordinating Council 3-machine, 9-bus system. MATLAB and PSCAD® simulations are employed to validate the approach. Moreover the insights gained from the vulnerability analysis of the WECC system are consistent with intuition.