The present disclosure is directed to systems and methods for mitigating or eliminating the effectiveness of a side channel attack, such as a Meltdown or Spectre type attack by selectively introducing a variable, but controlled, quantity of uncertainty into the externally accessible system parameters visible and useful to the attacker. The systems and methods described herein provide perturbation circuitry that includes perturbation selector circuitry and perturbation block circuitry. The perturbation selector circuitry detects a potential attack by monitoring the performance/timing data generated by the processor. Upon detecting an attack, the perturbation selector circuitry determines a variable quantity of uncertainty to introduce to the externally accessible system data. The perturbation block circuitry adds the determined uncertainty into the externally accessible system data. The added uncertainty may be based on the frequency or interval of the event occurrences indicative of an attack.