A method for protecting a mobile terminal device from cyber security threats, comprising: executing, by at least a processor in the mobile terminal device, test routines program codes stored in a non-transitory memory to configure the mobile terminal device to perform testing on at least one electrical utility device, wherein the mobile terminal device is configured to detect that the mobile terminal device is successfully connected only through one or both of a selected physical serial interface and a wired network interface, wherein the selected physical serial interface is connected to a device for facilitating the testing or to another electrical utility device under test and the wired interface is connected to the at least one electrical utility device; prior to executing a test routine by the mobile terminal device, switching the mobile terminal device to a test state by performing within the mobile terminal device in any sequence, the following: disabling an internal firewall of the mobile terminal device, disabling communication to one or more remaining network interfaces, and disabling connection to one or more remaining unselected physical serial interface for plug-in device port, such that existing communications or connections are terminated and new communications and connections are prevented; enabling communication to only one or both of the selected physical serial interface and the wired network interface; and performing the testing on the at least one electrical utility device according to the executed test routines under control of the mobile terminal device until completion. executing, by at least a processor in the mobile terminal device, test routines program codes stored in a non-transitory memory to configure the mobile terminal device to perform testing on at least one electrical utility device, wherein the mobile terminal device is configured to detect that the mobile terminal device is successfully connected only through one or both of a selected physical serial interface and a wired network interface, wherein the selected physical serial interface is connected to a device for facilitating the testing or to another electrical utility device under test and the wired interface is connected to the at least one electrical utility device; prior to executing a test routine by the mobile terminal device, switching the mobile terminal device to a test state by performing within the mobile terminal device in any sequence, the following: disabling an internal firewall of the mobile terminal device, disabling communication to one or more remaining network interfaces, and disabling connection to one or more remaining unselected physical serial interface for plug-in device port, such that existing communications or connections are terminated and new communications and connections are prevented; enabling communication to only one or both of the selected physical serial interface and the wired network interface; and disabling an internal firewall of the mobile terminal device, disabling communication to one or more remaining network interfaces, and disabling connection to one or more remaining unselected physical serial interface for plug-in device port, such that existing communications or connections are terminated and new communications and connections are prevented; enabling communication to only one or both of the selected physical serial interface and the wired network interface; and performing the testing on the at least one electrical utility device according to the executed test routines under control of the mobile terminal device until completion. <EOS>