Measurement of software security is a long-standing challenge to the research community. At the same time, practical security metrics and measurements are essential for secure software development. Hence, the need for metrics is more pressing now due to a growing demand for secure software. In this paper, we propose using a software system's attack surface measurement as an indicator of the system's security. We formalize the notion of a system's attack surface and introduce an attack surface metric to measure the attack surface in a systematic manner. Our measurement method is agnostic to a software system's implementation language and is applicable to systems of all sizes; we demonstrate our method by measuring the attack surfaces of small desktop applications and large enterprise systems implemented in C and Java. We conducted three exploratory empirical studies to validate our method. Software developers can mitigate their software's security risk by measuring and reducing their software's attack surfaces. Our attack surface reduction approach complements the software industry's traditional code quality improvement approach for security risk mitigation and is useful in multiple phases of the software development lifecycle. Our collaboration with SAP demonstrates the use of our metric in the software development process.

/pdf/an-attack-surface-metric-395l6r2ma5.pdf

An Attack Surface Metric

Cloud security is one of most important issues that has attracted a lot of research and development effort in past few years. Particularly, attackers can explore vulnerabilities of a cloud system and compromise virtual machines to deploy further large-scale Distributed Denial-of-Service (DDoS). DDoS attacks usually involve early stage actions such as multistep exploitation, low-frequency vulnerability scanning, and compromising identified vulnerable virtual machines as zombies, and finally DDoS attacks through the compromised zombies. Within the cloud system, especially the Infrastructure-as-a-Service (IaaS) clouds, the detection of zombie exploration attacks is extremely difficult. This is because cloud users may install vulnerable applications on their virtual machines. To prevent vulnerable virtual machines from being compromised in the cloud, we propose a multiphase distributed vulnerability detection, measurement, and countermeasure selection mechanism called NICE, which is built on attack graph-based analytical models and reconfigurable virtual network-based countermeasures. The proposed framework leverages OpenFlow network programming APIs to build a monitor and control plane over distributed programmable virtual switches to significantly improve attack detection and mitigate attack consequences. The system and security evaluations demonstrate the efficiency and effectiveness of the proposed solution.

NICE: Network Intrusion Detection and Countermeasure Selection in Virtual Network Systems

InkTag is a virtualization-based architecture that gives strong safety guarantees to high-assurance processes even in the presence of a malicious operating system. InkTag advances the state of the art in untrusted operating systems in both the design of its hypervisor and in the ability to run useful applications without trusting the operating system. We introduce paraverification, a technique that simplifies the InkTag hypervisor by forcing the untrusted operating system to participate in its own verification. Attribute-based access control allows trusted applications to create decentralized access control policies. InkTag is also the first system of its kind to ensure consistency between secure data and metadata, ensuring recoverability in the face of system crashes.

/pdf/inktag-secure-applications-on-an-untrusted-operating-system-36pg3vlits.pdf

InkTag: secure applications on an untrusted operating system

In contrast to testing, mathematical reasoning and formal verification can show the absence of whole classes of security vulnerabilities. We present the, to our knowledge, first complete, formal, machine-checked verification of information flow security for the implementation of a general-purpose microkernel; namely seL4. Unlike previous proofs of information flow security for operating system kernels, ours applies to the actual 8, 830 lines of C code that implement seL4, and so rules out the possibility of invalidation by implementation errors in this code. We assume correctness of compiler, assembly code, hardware, and boot code. We prove everything else. This proof is strong evidence of seL4's utility as a separation kernel, and describes precisely how the general purpose kernel should be configured to enforce isolation and mandatory information flow control. We describe the information flow security statement we proved (a variant of intransitive noninterference), including the assumptions on which it rests, as well as the modifications that had to be made to seL4 to ensure it was enforced. We discuss the practical limitations and implications of this result, including covert channels not covered by the formal proof.

/pdf/sel4-from-general-purpose-to-a-proof-of-information-flow-4nckx61jdw.pdf

seL4: From General Purpose to a Proof of Information Flow Enforcement

The rise of the Cloud Computing paradigm has led to security concerns, taking into account that resources are shared and mediated by a Hypervisor which may be targeted by rogue guest VMs and remote attackers. In order to better define the threats to which a cloud server's Hypervisor is exposed, we conducted a thorough analysis of the codebase of two popular open-source Hypervisors, Xen and KVM, followed by an extensive study of the vulnerability reports associated with them. Based on our findings, we propose a characterization of Hypervisor Vulnerabilities comprised of three dimensions: the trigger source (i.e. where the attacker is located), the attack vector (i.e. the Hypervisor functionality that enables the security breach), and the attack target (i.e. the runtime domain that is compromised). This can be used to understand potential paths different attacks can take, and which vulnerabilities enable them. Moreover, most common paths can be discovered to learn where the defenses should be focused, or conversely, least common paths can be used to find yet-unexplored ways attackers may use to get into the system.

/pdf/characterizing-hypervisor-vulnerabilities-in-cloud-computing-3gjk2ikoac.pdf

Characterizing hypervisor vulnerabilities in cloud computing servers

This work is a sequel of the studies in the analysis of vulnerabilities in computer systems. It applied boolean algebras to develop a mathematical model describing the exploits of the NVD data source when using the classification based on the concept of measurement. Quasimeasure has been offered for the boolean algebra, proved that she is a measure from the point of view of measure theory. Shows that the algebraic structure is also algebra of events.

Воробьев Антон Александрович

Papers

Анализ уязвимостей вычислительных систем на основе алгебраических структур и потоков данных National Vulnerability Database