We examine the feasibility of an attack on themeasurements that will be used by integrated volt-var control(VVC) in future smart power distribution systems. The analysisis performed under a variety of assumptions of adversarycapability regarding knowledge of details of the VVC algorithmused, system topology, access to actual measurements, andability to corrupt measurements. The adversary also faces anoptimization problem, which is to maximize adverse impactwhile remaining stealthy. This is achieved by first identifyingsets of measurements that can be jointly but stealthily corrupted.Then, the maximal impact of such data corruptionis computed for the case where the operator is unaware ofthe attack and directly applies the configuration from theintegrated VVC. Furthermore, since the attacker is constrainedto remaining stealthy, we consider a game-theoretic frameworkwhere the operator chooses settings to maximize observabilityand constrain the adversary action space.