Patent ID: 8630938

Claim:
A method of detecting a fraudulent activity at a network-based transaction facility, the method comprising: generating a first identifier associated with a first user identity, the first identifier to be stored in a shill cookie on a client machine of the first user, the first identifier being generated responsive to at least a first of a plurality of triggering events with respect to the network-based transaction facility, the network-based transaction facility being coupled to the client machine via a network; generating a second identifier associated with a second user identity, the second user identity to be stored in the shill cookie on the client machine, the second identifier being generated responsive to at least a second of the plurality of triggering events with respect to the network-based transaction facility; receiving information stored on the shill cookie at the network-based transaction facility; and detecting a potentially fraudulent activity by detecting a lack of correspondence between the first identifier and the second identifier.