Wireless sensor networks are vulnerable to a wide variety of threats and node replication attack is of the most critical concern. In node replication attack, an adversary creates many replicas after compromising and obtaining all the secret credentials of the captured node. These replicas are deployed by an adversary at strategic positions of the network in order to launch many insidious attacks within the sensor network. Node replication attack becomes more sophisticated and harmful when it appears in the form of masked replication attack. In masked replication attack all the neighbors of a clone node are compromised so that an adversary is able to shelter its clone node from being detected by the detection process. To counter node replication attack many witness based techniques have been proposed but almost of them are unable to detect masked replication attack. Some of the existing witness based techniques proposed for the node replication attack have promising results for countering node replication attack but not a single one of them have provided a solution for masked replication attack which is a specialized type of node replication attack. © 2013 AISTI.