Publishing a book on a subject as dynamic as internet worms can never result in a complete volume. The near-weekly outbreaks of modified versions of old worms and completely new designs is enough to frustrate the efforts of even the most prolific anti-virus software developers, let alone those who try to provide an overview of their study. Nevertheless, Nazario accomplishes a clear and concise summary of the state of worms today. Seeded by a paper ('The Future of Internet Worms', Nazario, Anderson, Connelly, Wash) written in 2001, Defense Against Internet Worms encourages the reader to focus on the directions worm development might take in the future, with a specific view toward anticipation of, and prepartion for, future attacks.
The book begins with a discussion of the departure worms take from traditional computer virii. An outline of the benefits for the black-hat toward a worm-based attack, as well as a brief analysis of the threat model posed by worms, provide ample reason for the computer security professional to take the study of internet worms very seriously. Beyond this introduction, the book is laid out in four major sections. The first introduces to the reader some background information crucial to the study of worms. The author discusses the history and taxonomy of past worm outbreaks, from their sci-fi origins (think John Brunner's "Shockwave Rider") through modern-day outbreaks. A thorough analysis of various worms' traffic patterns is presented, with data broken down by infection rates, number of infected hosts, and number of sources probing specific subnets. Finally, the construction and lifecycle of worms are presented, with particular attention paid to the interaction between the worms' propagation techniques and the progression of their lifecycles.
The second section of the book (ch. 6 - 8) studies the trends exhibited by past worm outbreaks. Beginning with an examination of the processes and mechanisms of infection, it progresses on to a survey of the network topologies generated by a worm's distribution. Specific infection patterns are examined, along with case studies of worm outbreaks that have exhibited such patterns. Further, this section examines the common characteristics of vulnerable targets, from older UNIX and VMS mainframes through desktop systems onward to infrastructure equipment and embedded systems. A discussion of the payload transmission methods that have made recent worm attacks so devastatingly effective, and an explaination of why liberal use of a clue-hammer on users is not by itself enough to control and prevent further outbreaks, complement chapter nine's analysis and speculation of the future of internet worms.
Section three (ch. 9 - 11) focuses on worm detection strategies, and is more distinctly aimed at the already-overworked network security professional. Effective methods of detecting scans and analyzing a worm's scan engine are presented with a focus on timely and efficient protection from further infection. Monitoring techniques for quickly recognizing, analyzing and responding to worm outbreaks leads into a detailed description of well-placed honeypots and dark network monitors ("black holes"). Discussion of the (so-far) most effective method of worm detection, signature analysis, completes the section, and covers host-based and logfile signatures, along with a brief overview of analyzing logfiles using commonly available utilities.
The final section of the book (ch. 12 - 16), per the book's namesake, aims at defense strategies against worm outbreaks. Beginning with the obvious first steps which anyone reading the book ought to have implemented (firewalls, virus detection software, sandboxing, and patching-patching-patching), the section progresses into less widely used but equally important proxy-based defense methods, and continues on to cover slowing down infection rates and fighting back against existing worm networks. For the sake of thoroughness, an overview of the legal implications of attacking worm nodes receives its fair share of attention simply to alert the reader of the dangers of proactive defense.
Defense Against Internet Worms is decidedly aimed at the experienced network security professional, but holds a much broader appeal than most technical books. With its thorough historical analysis of worm progression over the past thirty years, anyone with even a remote interest in the past, present or future of the only network security issues to consistently make headlines in the mainstream press will find this both an entertaining and enlightening read. Overall, it makes a valuable addition to any geek's bookshelf.