Dependable Intrusion Tolerance: technology demo
The Dependable Intrusion Tolerance (DIT) architecture is a flexible, adaptive, and intrusion-tolerant server design. We briefly discuss its prototype implementation and validation, and demonstrate how it resists sample attacks.

title: Modeling multistep cyber attacks for scenario recognition
abstract: Efforts toward automated detection and identification of multistep cyber attack scenarios would benefit significantly from a methodology and language for modeling such scenarios. The Correlated Attack Modeling Language (CAML) uses a modular approach, where a module represents an inference step and modules can be linked together to detect multistep scenarios. CAML is accompanied by a library of predicates, which functions as a vocabulary to describe the properties of system states and events. The concept of attack patterns is introduced to facilitate reuse of generic modules in the attack modeling process. CAML is used in a prototype implementation of a scenario recognition engine that consumes first-level security alerts in real time and produces reports that identify multistep attack scenarios discovered in the alert stream.

title: Automatic analysis of firewall and network intrusion detection system configurations
abstract: Given a network that deploys multiple firewalls and network intrusion detection systems (NIDSs), ensuring that these security components are correctly configured is a challenging problem. Although models have been developed to reason independently about the effectiveness of firewalls and NIDSs, there is no common framework to analyze their interaction. This paper presents an integrated, constraint-based approach for modeling and reasoning about these configurations. Our approach considers the dependencies among the two types of components, and can reason automatically about their combined behavior. We have developed a tool for the specification and verification of networks that include multiple firewalls and NIDSs, based on this approach. This tool can also be used to automatically generate NIDS configurations that are optimal relative to a given cost function.

title: Time Lower Bounds for Permutation Routing on Multi-Dimensional Bused Meshes
abstract: We present time lower bounds for the permutation routing problem on three- and higher-dimensional n x…x n meshes with buses. We prove an (r–1)n/r lower bound for the general case of an r-dimensional bused mesh, r≥2, which is not as strong for low-dimensional as for higher-dimensional cases. We then use a different approach to construct a 0.705n lower bound for the three-dimensional case.

title: An Architecture for an Adaptive Intrusion-Tolerant Server
abstract: We describe a general architecture for intrusion-tolerant enterprise systems and the implementation of an intrusion-tolerant Web server as a specific instance. The architecture comprises functionally redundant COTS servers running on diverse operating systems and platforms, hardened intrusion-tolerance proxies that mediate client requests and verify the behavior of servers and other proxies, and monitoring and alert management components based on the EMERALD intrusion-detection framework. Integrity and availability are maintained by dynamically adapting the system configuration in response to intrusions or other faults. The dynamic configuration specifies the servers assigned to each client request, the agreement protocol used to validate server replies, and the resources spent on monitoring and detection. Alerts trigger increasingly strict regimes to ensure continued service, with graceful degradation of performance, even if some servers or proxies are compromised or faulty. The system returns to less stringent regimes as threats diminish. Servers and proxies can be isolated, repaired, and reinserted without interrupting service.

title: Routing with Locality on Meshes with Buses
abstract: Routing with locality is studied for meshes with buses. In this problem, packets' distances are bounded by a value,d, which is less than the diameter of the network. This problem arises naturally when specific known algorithms are implemented on meshes. Solving this problem in ordinary meshes requires at least a routing time ofdsteps. To do better than this, we propose adding a kind of short bus to ordinary meshes. By using a technique which we call iterative walk-and-ride, we show how the routing time can be reduced by approximately one-third for solving the problem (including the multipacket version) on one- and two-dimensional short-bus meshes. The bounds we develop are tight.

title: Efficient video similarity measurement with video signature
abstract: The proliferation of video content on the Web makes similarity detection an indispensable tool in Web data management, searching, and navigation. We propose a number of algorithms to efficiently measure video similarity. We define video as a set of frames, which are represented as high dimensional vectors in a feature space. Our goal is to measure ideal video similarity (IVS), defined as the percentage of clusters of similar frames shared between two video sequences. Since IVS is too complex to be deployed in large database applications, we approximate it with Voronoi video similarity (VVS), defined as the volume of the intersection between Voronoi cells of similar clusters. We propose a class of randomized algorithms to estimate VVS by first summarizing each video with a small set of its sampled frames, called the video signature (ViSig), and then calculating the distances between corresponding frames from the two ViSigs. By generating samples with a probability distribution that describes the video statistics, and ranking them based upon their likelihood of making an error in the estimation, we show analytically that ViSig can provide an unbiased estimate of IVS. Experimental results on a large dataset of Web video and a set of MPEG-7 test sequences with artificially generated similar versions are provided to demonstrate the retrieval performance of our proposed techniques.

title: Alert-driven e-service management
abstract: Process management technology has recently been employed not only within businesses but also in provision of e-services over the Internet. Urgent requests and critical messages in these systems (referred to as alerts) should be delivered and handled timely. In particular, humans are often involved in critical conditions. Presently, most e-service systems cannot address these requirements, and alerts are often handled in an ad-hoc manner. In this paper, we propose a sophisticated alert management system for effective e-service integration under urgent constraints. We develop a model for specifying alerts, in which alerts are associated with service requests and a set of parameters are captured for their routing. The alert monitor matches the service provider to receive an alert, based on the alert specification. We then propose a routing mechanism that is initiated when the alert message is not acknowledged or serviced within the deadline, so that the alert can be forwarded to other suitable services if necessary. Monitoring is especially essential to ensure timeliness and availability of services, otherwise suitable exceptions should be raised and handled. We outline our implementation framework of an alert management system (AMS) which includes Web services for B2B interactions, together with multiple-platform support for human users. We demonstrate our approach with an example medical house-call AMS.

title: Performance Aware Service Pool in Dependable Service Oriented Architecture
abstract: As a popular approach to dependable service oriented architecture (SOA), a service pool collects a set of services that provide the same functionality by different service providers for achieving desired reliability. However, if the tradeoff between reliability and other important qualities, e.g., performance, has to be considered, the construction and management of a service pool become much more complex. In this paper, an automated approach to this problem is presented. Based on the investigation of service pools in the typical triangle SOA model, two challenges critical to the effectiveness and efficiency of service pools are identified, including which services should be held by a pool and what order these services are invoked in. A set of algorithms are designed to address the two challenges and then a service pool can be automatically constructed and managed for given reliability and performance requirements in polynomial time. The approach is demonstrated on a J2EE based service platform and the comparison results between different pooling algorithms are evaluated.

title: A commutative encrypted protocol for the privacy protection of watermarks in digital contents
abstract: Analysis by Forrester research revealed that 18% of global exports will flow online in 2004 and that the volume of e-commerce will surpass $400 billion. Digital rights protection is a major issue in the e-commerce of multimedia contents. Watermarking technology has been proposed as a promising enabling technology for the rights protection of multimedia digital contents. A unique watermark is embedded in each piece of multimedia contents before it is distributed to a customer. When unauthorized copies of a piece of contents are found, the customer who owns the contents can be readily identified by means of the embedded watermark. However, the unauthorized copies may also come from the content provider itself. It is therefore a challenging problem to determine whether an unauthorized copy is distributed by an unethical customer or by an unethical content provider. In this paper, we propose a watermarking protocol to address the problem using cryptographic technologies. Our protocol employs a commutative encryption algorithm to protect the privacy of watermarks. Information is doubly locked by two encryption keys kept separately by a customer and a content provider. In the protocol, a customer only gets a piece of watermarked multimedia contents in a transaction and the content provider has no idea how the watermark is formed. This facilitates the authority to determine the unethical party in case of unauthorized distribution of digital contents. We also discuss a couple of common attacks and show that our protocol can defend successfully against them.

title: Applying generic timing tests for distributed multimedia software systems
abstract: With recent advances in network technologies and computing power, multimedia systems have become a popular means for information delivery. However, testing of these systems is difficult. Due to incomplete control of their runtime and communication environment, precise temporal properties of multimedia systems are nonreproducible. Traditional software testing, which mainly deals with functional correctness, cannot be directly applied to testing temporal properties. Furthermore, time points are hard to be measured exactly, and in this sense are nondeterministic and nonreproducible. To address this problem, we propose a framework for testing the generic temporal properties of media objects in distributed multimedia software systems (DMSS). The timing properties are based on Allen's basic binary temporal relations between two objects, which can be extended to cover multiple objects. We have developed techniques for test case generation, and test result analysis based on a distributed tester architecture. Test templates are used in test case generation to reduce the possibility of human error, and the entire testing procedure can be automated. A prototype system has been built to test a DEC HPAS multimedia presentation system, which is a multimedia system supporting W3C's SMIL standard. Detailed discussions on practical issues illustrated with a number of actual tests are given. Experimental results have shown that our framework is effective in detecting errors in temporal properties. Furthermore, ways to reduce the test effort have been discussed, and guidelines for coming up with criteria for verdict computation based on the real-time requirements of the applications have been suggested.