A computer-implemented method for preventing modification of network resources in the absence of a user's consent is disclosed. The method may comprise: 1) identifying an attempt to modify a network resource, 2) administering a human-verification test, and 3) determining, based on the outcome of the human-verification test, whether to prevent modification of the network resource. In addition, a computer-implemented method for preventing unauthorized communication with network resources may comprise: 1) identifying a communication attempt between a network resource and an untrusted resource, 2) determining whether communication between the network resource and the untrusted resource is authorized, and 3) determining, based on whether communication between the network resource and the untrusted resource is authorized, whether to allow communication between the network resource and the untrusted resource. Corresponding systems and computer-readable media are also disclosed.