NISTIR 7788 August 2011 Today's information systems face sophisticated attackers who combine multiple vulnerabilities to penetrate networks with devastating impact. The overall security of an enterprise network cannot be determined by simply counting the number of vulnerabilities. To more accurately assess the security of enterprise systems, one must understand how vulnerabilities can be combined and exploited to stage an attack. Composition of vulnerabilities can be modeled using probabilistic attack graphs, which show all paths of attacks that allow incremental network penetration. Attack likelihoods are propagated through the attack graph, yielding a novel way to measure the security risk of enterprise systems. This metric for risk mitigation analysis is used to maximize the security of enterprise systems. This methodology based on probabilistic attack graphs can be used to evaluate and strengthen the overall security of enterprise networks. Why buy a book you can download for free? First you gotta find it and make sure it's the latest version (not always easy). Then you gotta print it using a network printer you share with 100 other people - and its outta paper - and the toner is low (take out the toner cartridge, shake it, then put it back). If it's just 10 pages, no problem, but if it's a 250-page book, you will need to punch 3 holes in all those pages and put it in a 3-ring binder. Takes at least an hour. An engineer that's paid $75 an hour has to do this himself (who has assistant's anymore?). If you are paid more than $10 an hour and use an ink jet printer, buying this book will save you money. It's much more cost-effective to just order the latest version from Amazon.com This book is published by 4th Watch Books and includes copyright material. We publish compact, tightly-bound, full-size books (8 1⁄2 by 11 inches), with glossy covers. 4th Watch Books is a Service Disabled Veteran-Owned Small Business (SDVOSB), and is not affiliated with the National Institute of Standards and Technology. For more titles published by 4th Watch Books, please visit: cybah.webplus.net A full copy of all the pertinent cybersecurity standards is available on DVD-ROM in the CyberSecurity Standards Library disc which is available at Amazon.com. NIST SP 500-299 NIST Cloud Computing Security Reference Architecture NIST SP 500-291 NIST Cloud Computing Standards Roadmap Version 2 NIST SP 500-293 US Government Cloud Computing Technology Roadmap Volume 1 & 2 NIST SP 500-293 US Government Cloud Computing Technology Roadmap Volume 3 DRAFT

This book examines different aspects of network security metrics and their application to enterprise networks. One of the most pertinent issues in securing mission-critical computing networks is the lack of effective security metrics which this book discusses in detail. Since “you cannot improve what you cannot measure”, a network security metric is essential to evaluating the relative effectiveness of potential network security solutions. The authors start by examining the limitations of existing solutions and standards on security metrics, such as CVSS and attack surface, which typically focus on known vulnerabilities in individual software products or systems. The first few chapters of this book describe different approaches to fusing individual metric values obtained from CVSS scores into an overall measure of network security using attack graphs. Since CVSS scores are only available for previously known vulnerabilities, such approaches do not consider the threat of unknown attacks exploiting the so-called zero day vulnerabilities. Therefore, several chapters of this book are dedicated to develop network security metrics especially designed for dealing with zero day attacks where the challenge is that little or no prior knowledge is available about the exploited vulnerabilities, and thus most existing methodologies for designing security metrics are no longer effective. Finally, the authors examine several issues on the application of network security metrics at the enterprise level. Specifically, a chapter presents a suite of security metrics organized along several dimensions for measuring and visualizing different aspects of the enterprise cyber security risk, and the last chapter presents a novel metric for measuring the operational effectiveness of the cyber security operations center (CSOC). Security researchers who work on network security or security analytics related areas seeking new research topics, as well as security practitioners including network administrators and security architects who are looking for state of the art approaches to hardening their networks, will find this book helpful as a reference. Advanced-level students studying computer science and engineering will find this book useful as a secondary text.

This book examines different aspects of network security metrics and their application to enterprise networks. One of the most pertinent issues in securing mission-critical computing networks is the lack of effective security metrics which this book discusses in detail. Since “you cannot improve what you cannot measure”, a network security metric is essential to evaluating the relative effectiveness of potential network security solutions. The authors start by examining the limitations of existing solutions and standards on security metrics, such as CVSS and attack surface, which typically focus on known vulnerabilities in individual software products or systems. The first few chapters of this book describe different approaches to fusing individual metric values obtained from CVSS scores into an overall measure of network security using attack graphs. Since CVSS scores are only available for previously known vulnerabilities, such approaches do not consider the threat of unknown attacks exploiting the so-called zero day vulnerabilities. Therefore, several chapters of this book are dedicated to develop network security metrics especially designed for dealing with zero day attacks where the challenge is that little or no prior knowledge is available about the exploited vulnerabilities, and thus most existing methodologies for designing security metrics are no longer effective. Finally, the authors examine several issues on the application of network security metrics at the enterprise level. Specifically, a chapter presents a suite of security metrics organized along several dimensions for measuring and visualizing different aspects of the enterprise cyber security risk, and the last chapter presents a novel metric for measuring the operational effectiveness of the cyber security operations center (CSOC). Security researchers who work on network security or security analytics related areas seeking new research topics, as well as security practitioners including network administrators and security architects who are looking for state of the art approaches to hardening their networks, will find this book helpful as a reference. Advanced-level students studying computer science and engineering will find this book useful as a secondary text.

Protection of enterprise networks from malicious intrusions is critical to the economy and security of our nation. This article gives an overview of the techniques and challenges for security risk analysis of enterprise networks. A standard model for security analysis will enable us to answer questions such as “are we more secure than yesterday” or “how does the security of one network configuration compare with another one”. In this article, we will present a methodology for quantitative security risk analysis that is based on the model of attack graphs and the Common Vulnerability Scoring System (CVSS). Our techniques analyze all attack paths through a network, for an attacker to reach certain goal(s).

Central to computer security are detecting attacks against systems and managing computer systems to mitigate threats to the system. Attacks exploit vulnerabilities in the system such as a programming flaw. Threats are vulnerabilities which could lead to an attack under certain circumstances. The key to the detection of attacks is discovering an ongoing attack against the system. Mitigating threats involves a continuous assessment of the vulnerabilities in the system and of the risk these vulnerabilities pose with respects to a security policy. Intrusion detection systems (IDS) are programs which detect attacks. The goal is to issue alerts only when an actual attack occurs, but also to not miss any attacks. The biological immune system provides a compelling model on which to base an IDS. This work adds the biological concepts of positive selection and collaboration to artificial immune systems to achieve a better attack detection rate without unduly raising the false alarm rate. Attack graphs assess the threat to the system by showing the composition of vulnerabilities in the system. The key issues with attack graphs are to large networks, ease of coding new attacks into the model, incomplete network information, visualization of the graph and automatic analysis of the graph. This work presents an abstract class model that aggregates individual attacks into abstract classes. Through these abstractions, scalability is greatly increased and the codification of new attacks into the model is made easier when compared to the current approach that models each attack. Clustering of identical machines is used to reduce the visual complexity of the graph and also to increase scalability. Incomplete network information is handled by allowing "what if" evaluations where an administrator can hypothesize about the existence of certain vulnerabilities in the system and investigate their consequences.