Real - Time Intrusion Detection

Distributed mission critical systems require support for ultra-secure communication, in which intrusions must be detected and suppressed in real time, possibly before the aaected messages reach the receiver. When the distributed application has real-time requirements , the eeects of intrusion are particularly severe. In addition to covered channels and potentially tampered data at the receiver, such systems may experience violations of timing requirements and timing instabilities in components not directly related to the intrusion. Systems with real-time requirements have admission and access control mechanisms in place to ensure that timing requirements can be met during normal operation. Such admission control mechanisms require load prooles of traf-c (for example in form of leaky bucket descriptors) so that resources can be appropriately allocated to meet application requirements during system operation. In this paper, we report on our project aiming at real-time detection of intrusions in ATM networks. We take advantage of the speciication of the traac proole during connection setup, and use a traac modeling technique to determine the proole of the traac on the connection in an arbitrary point in the network, thus providing a base line for detection of load deviations. We designed and analyzed a security device that uses the proole information, detects violations. The traac is modeled in an accurate but eecient manner. As a result, our device is able to detect an intrusion within 25 s, yet is simple enough to be economically realized in existing VLSI technology.