1. A system for validating an active terminal session, comprising: a processing device in communication with an idle session timer, an authorized terminal device, computer readable memory and a computer readable storage media; first instructions to analyze non-idle keystroke input from an authorized terminal device and ascertain human-like behavior as a function of a timing characteristic of the keystroke input during an open active terminal session; second instructions to determine whether the terminal device input is likely from a human user or from an automaton in response to the timing characteristic; and third instructions to: terminate the session, generate a time-out warning to the user or present a challenge to the user in response to a determination that the terminal device input is likely from an automaton; manipulate the idle session timer in response to a determination that the terminal device input is likely from a human user or to the user passing the challenge; or terminate the session in response to the user failing the challenge; wherein the timing characteristic is at least one of a maximum generation rate, a burstiness indicated by keystroke intensity over a given time period, and a predictable keystroke sequence delay between certain keystrokes in a specified sequence due to an ease or a difficulty of finger manipulations required to generate the specific sequence through a known input element; and wherein the first, second and third program instructions are stored on the computer readable storage media for execution by the processing device via the computer readable memory.