With the growing deployment of host and network intrusion detection systems, managing reports from these systems becomes critically important. We present a probabilistic approach to alert correlation, extending ideas from multisensor data fusion. Features used for alert correlation are based on alert content that anticipates evolving IETF standards. The probabilistic approach provides a unified mathematical framework for correlating alerts that match closely but not perfectly, where the minimum degree of match required to fuse alerts is controlled by a single configurable parameter. Only features in common are considered in the fusion algorithm. For each feature we define an appropriate similarity function. The overall similarity is weighted by a specifiable expectation of similarity. In addition, a minimum similarity may be specified for some or all features. Features in this set must match at least as well as the minimum similarity specification in order to combine alerts, regardless of the goodness of match on the feature set as a whole. Our approach correlates attacks over time, correlates reports from heterogeneous sensors, and correlates multiple attack steps.

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Probabilistic Alert Correlation

A computer-implemented intrusion detection system and method that monitors a computer system in real-time for activity indicative of attempted or actual access by unauthorized persons or computers. The system detects unauthorized users attempting to enter into a computer system by comparing user behavior to a user profile, detects events that indicate an unauthorized entry into the computer system, notifies a control function about the unauthorized users and events that indicate unauthorized entry into the computer system and has a control function that automatically takes action in response to the event. The user profiles are dynamically constructed for each computer user when the computer user first attempts to log into the computer system and upon subsequent logins, the user's profile is dynamically updated. By comparing user behavior to the dynamically built user profile, false alarms are reduced. The system also includes a log auditing function, a port scan detector and a session monitor function.

Intrusion detection system

A signature based dynamic network intrusion detection system (IDS) includes attack signature profiles which are descriptive of characteristics of known network security violations. The attack signature profiles are organized into sets of attack signature profiles according to security requirements of network objects on a network. Each network object is assigned a set of attack signature profiles which is stored in a signature profile memory together with association data indicative of which sets of attack signature profiles correspond to which network objects. A monitoring device monitors network traffic for data addressed to the network objects. Upon detecting a data packet addressed to one of the network objects, packet information is extracted from the data packet. The extracted information is utilized to obtain a set of attack signature profiles corresponding to the network object based on the association data. A virtual processor executes instructions associated with attack signature profiles to determine if the packet is associated with a known network security violation. An attack signature profile generator is utilized to generate additional attack signature profiles configured for processing by the virtual processor in the absence of any corresponding modification of the virtual processor.

Dynamic signature inspection-based network intrusion detection

A port profiling system (155) detects unauthorized network usage (110). The port profiling system analyzes network communications (101, 199)to determine the service ports being used (181, 182, 183, 184, 185, 186). The system collects flow data (101, 162) from packet headers (162) between two hosts or Internet Protocol (IP) addresses. The collected flow data (160) is analyzed to determin e the associated network service provided (166). A host data structure (160, 166) is maintained containing a profile of the network services normally associated with the host (162). If the observed network service is not one of the normal network services performed as defined by the port profile (160, 166) for that host, an alarm signal is generated (630) and action (642) can be taken based upon the detection of an Out of Profile network service (610). An Out of Profile operation can indicate the operation of a Trojan Horse program (120) on the host, a scanning probe, or the existence of a non-approved network application that has been installed (160, 162, 120).

Network port profiling

The present invention is directed to systems and methods for detecting unsolicited and threatening communications and communicating threat information related thereto. Threat information is received from one or more sources; such sources can include external security databases and threat information data from one or more application and/or network layer security systems. The received threat information is reduced into a canonical form. Features are extracted from the reduced threat information; these features in conjunction with configuration data such as goals are used to produce rules. In some embodiments, these rules are tested against one or more sets of test data and compared against the same or different goals; if one or more tests fail, the rules are refined until the tests succeed within an acceptable margin of error. The rules are then propagated to one or more application layer security systems.

Systems and methods for message threat management

This is a system and method for network surveillance and detection of attempted intrusions, or intrusions, into the network and into computers connected to the network. The System functions are: (A) intrusion detection monitoring, (B) real-time alert, (C) logging of potential unauthorized activity, and (D) incident progress analysis and reporting. Upon detection of any attempts to intrude, the System will initiate a log of all activity between the computer elements involved and send an alert to a monitoring console. When a log is initiated, the network continues to be monitored by a primary surveillance system. A secondary monitoring process is started which interrogates the activity log in real-time and sends additional alerts reporting the progress of the suspected intruder.

John Reed Harrison

Papers

Network surveillance system