Abstract not found

Almost thirty years ago a vulnerability assessment of Multics identified significant vulnerabilities, despite the fact that Multics was more secure than other contemporary (and current) computer systems. Considerably more important than any of the individual design and implementation flaws was the demonstration of subversion of the protection mechanism using malicious software (e.g., trap doors and Trojan horses). A series of enhancements were suggested that enabled Multics to serve in a relatively benign environment. These included addition of “Mandatory Access Controls ” and these enhancements were greatly enabled by the fact the Multics was designed from the start for security. However, the bottom-line conclusion was that “restructuring is essential ” around a verifiable “security kernel ” before using Multics (or any other system) in an open environment (as in today’s Internet) with the existence of well-motivated professional attackers employing subversion. The lessons learned from the vulnerability assessment are highly applicable today as governments and industry strive (unsuccessfully) to “secure ” today’s weaker operating systems through add-ons, “hardening”, and intrusion detection schemes. 1

Researchers have argued that the best way to construct a secure system is to proactively integrate security into the design of the system. However, this tenet is rarely followed because of economic and practical considerations. Instead, security mechanisms are added as the need arises, by retrofitting legacy code. Existing techniques to do so are manual and ad hoc, and often result in security holes. We present program analysis techniques to assist the process of retrofitting legacy code for authorization policy enforcement. These techniques can be used to retrofit legacy servers, such as X window, web, proxy, and cache servers. Because such servers manage multiple clients simultaneously, and offer shared resources to clients, they must have the ability to enforce authorization policies. A developer can use our techniques to identify security-sensitive locations in legacy servers, and place reference monitor calls to mediate these locations. We demonstrate our techniques by retrofitting the X11 server to enforce authorization policies on its X clients. 1.

project, which is producing an openly distributed worked example of how high assurance trusted computing components can be built. The TCX project encompasses four related activities: Creation of a prototype framework for rapid high assurance system development; Development of a reference-implementation trusted computing component; Evaluation of the component for high assurance; and Open dissemination of results related to the first three activities. The project’s open development methodology will provide widespread availability of key high assurance enabling technologies and ensure transfer of knowledge and capabilities for trusted computing to the next generation of developers, evaluators and educators. I.

This paper describes a research project to engineer a security kernel for Multics, a general-purpose, remotely accessed, multiuser computer system. The goals are to identify the minimum mechanism that must be correct to guarantee computer enforcement of desired constraints on information access, to simplify the structure of that minimum mechanism to make verification of correctness by auditing possible, and to demonstrate by test'implementation that the security kernel so developed is capable of supporting the functionality of Multics completely and efficiently. The paper presents the overall viewpoint and plan for the project and discusses initial strategies being employed to define and structure the security kernel.

The computer systems security arms race between attackers and defenders has largely taken place in the domain of software systems, but as hardware complexity and design processes have evolved, novel and potent hardware-based security threats are now possible. This paper presents a hybrid hardware/software approach to defending against malicious hardware. We propose BlueChip, a defensive strategy that has both a design-time component and a runtime component. During the design verification phase, BlueChip invokes a new technique, unused circuit identification (UCI), to identify suspicious circuitry—those circuits not used or otherwise activated by any of the design verification tests. BlueChip removes the suspicious circuitry and replaces it with exception generation hardware. The exception handler software is responsible for providing forward progress by emulating the effect of the exceptiongenerating instruction in software, effectively providing a detour around suspicious hardware. In our experiments, BlueChip is able to prevent all hardware attacks we evaluate while incurring a small runtime overhead. 1

The threat of attack by computer viruses is in reality a very small part of a much more general threat, specifically attacks aimed at subverting computer security. This paper examines computer viruses as malicious logic in a research and development environment, relates them to various models of security and integrity, and examines current research techniques aimed at controlling the threats viruses in particular, and malicious logic in general, pose to computer systems. Finally, a brief examination of the vulnerabilities of research and development systems that malicious logic and computer viruses may exploit is undertaken. 1.

Existing applications often contain security holes that are not patched until after the system has already been compromised. Even when software updates are applied to address security issues, they often result in system services being unavailable for some time. To address these system security and availability issues, we have developed peas and pods. A pea provides a least privilege environment that can restrict processes to the minimal subset of system resources needed to run. This mechanism enables the creation of environments for privileged program execution that can help with intrusion prevention and containment. A pod provides a group of processes and associated users with a consistent, machine-independent virtualized environment. Pods are coupled with a novel checkpoint-restart mechanism which allows processes to be migrated across minor operating system kernel versions with different security patches. This mechanism allows system administrators the flexibility to patch their operating systems immediately without worrying over potential loss of data or needing to schedule system downtime. We have implemented peas and pods in Linux without requiring any application or operating system kernel changes. Our measurements on real world desktop and server applications demonstrate that peas and pods impose little overhead and enable secure isolation and migration of untrusted applications.

This paper proposes a methodology to develop countermeasures against code injection attacks, and validates the methodology by working out a specific countermeasure. This methodology is based on modeling the execution environment of a program. Such a model is then used to build countermeasures. The paper justifies the need for a more structured approach to protect programs against code injection attacks: we examine advanced techniques for injecting code into C and C++ programs and we discuss state-of-the -art (often ad hoc) approaches that typically protect singular memory locations. We validate our methodology by building countermeasures that prevent attacks by protecting a broad variety of memory locations that may be used by attackers to perform code injections. The paper evaluates our approach and discusses ongoing and future work.

The development of a Common Criteria protection profile for high-robustness separation kernels requires explicit modifications of several Common Criteria requirements as well as extrapolation from existing (e.g., medium robustness) guidance and decisions. The draft U.S. Government Protection Profile for Separation Kernels in Environments Requiring High Robustness (SKPP) is intended to be applicable to a class of products (the target of evaluation, or TOE) that includes, but is not limited to, real time and embedded systems. This paper describes certain SKPP concepts and requirements and provides underlying motivations and rationale for their inclusion in the SKPP. Primary areas of focus are the security requirements regarding information flow, dynamic configuration, and the application of the principle of least privilege to restrict actions of active entities.