1. A system for blocking transmission of tainted data comprising: a client device generating a data request for retrieving data from a non-trusted entity via a network; and a gateway communicatively coupled to the client device and to the network, the gateway configured to receive computer code from the non-trusted entity via the network, execute the computer code, track the execution of the computer code to determine whether the computer code attempts to access tainted data and transmit the tainted data to the non-trusted entity and, responsive to determining that the computer code has attempted to access tainted data, transmit the tainted data to the non-trusted entity, blocking the transmission of the tainted data to the non-trusted entity.