The system and method for passively identifying encrypted and interactive network sessions described herein may distribute a passive vulnerability scanner in a network, wherein the passive vulnerability scanner may observe traffic travelling across the network and reconstruct a network session from the observed traffic. The passive vulnerability scanner may then analyze the reconstructed network session to determine whether the session was encrypted or interactive (e.g., based on randomization, packet timing characteristics, or other qualities measured for the session). Thus, the passive vulnerability scanner may monitor the network in real-time to detect any devices in the network that run encrypted or interactive services or otherwise participate in encrypted or interactive sessions, wherein detecting encrypted and interactive sessions in the network may be used to manage changes and potential vulnerabilities in the network.