An attack analyzer includes: a security log acquisition unit acquiring a security log including an abnormality detection signal generated by a security sensor mounted on an electronic control device constituting an electronic control system and indicating that the security sensor has detected an abnormality; a failure information acquisition unit acquiring failure information indicating a failure occurred in the electronic control device; a prediction table storage unit storing a prediction table showing a correspondence relationship between a predicted attack route in the electronic control system and a predicted abnormality detection signal predicted to be generated by the security sensor; an attack route estimation unit; and an attack information output unit outputting attack information indicating the attack route.