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Congressman Stephen Horn, R-CA Chairman

Oversight  hearing on

"Information Technology -- Essential Yet Vulnerable:
How Prepared Are We for Attacks?

September 26, 2001

Testimony of 

Richard D. Pethia
CERT Centers
Software Engineering Institute
Carnegie Mellon University

before the 

Subcommittee on Government Efficiency, 
Financial Management 
and Intergovernmental Relations 


Mr. Chairman and Members of the Subcommittee: My name is Rich Pethia. I am the director of the CERTŪ Centers, which include the CERT Coordination Center (CERT/CC) and CERT Analysis Center (CERT/AC). Thank you for the opportunity to testify on computer security issues that affect the government. Today I will discuss the vulnerability of information technology on the Internet, including information about the Nimda worm, and how prepared I believe the nation is for cyber attacks such as Nimda.

My perspective comes from the work we do at the CERT Centers, which are part of the Survivable Systems Initiative of the Software Engineering Institute, a federally funded research and development center operated by Carnegie Mellon University. We have 13 years of experience with computer and network security. The CERT/CC was established in 1988, after an Internet "worm" became the first Internet security incident to make headline news, acting as a wake-up call for network security. In response, the CERT/CC was established at the SEI. The center was activated in just two weeks, and we have worked hard to maintain our ability to react quickly. The CERT/CC staff has handled well over 63,000 incidents and cataloged more than 3,700 computer vulnerabilities.

The CERT Analysis Center, established just last year, addresses the threat posed by rapidly evolving, technologically advanced forms of cyber attacks. Working with sponsors and associates, the CERT Analysis Center collects and analyzes information assurance data to develop detection and mitigation strategies that provide high-leverage solutions to information assurance problems, including countermeasures for new vulnerabilities and emerging threats. The CERT Analysis Center builds upon the work of the CERT Coordination Center.

The CERT Centers are now recognized by both government and industry as a neutral, authoritative source of data and expertise on information assurance. In addition to handling reports of computer security breaches and vulnerabilities in network-related technology, we identify preventive security practices, conduct research, and provide training to system administrators, managers, and incident response teams. More details about our work are attached to the end of this testimony (see Survivable Systems Initiative).

The Nimda Worm Illustrates How Prepared We Are for Attacks

The recent attacks by the Nimda, or W32/Nimda, worm demonstrate our vulnerability. The worm modifies web documents (files ending with .htm, .html, and .asp) and certain executable files found on the systems it infects. It then creates numerous copies of itself under various file names. It scans the network for vulnerable computers and propagates through email, thereby causing some sites to experience denial of service or degraded performance. Computers that have been compromised are also at high risk for being used for attacks on other Internet sites.

One of Nimda’s behaviors is to attack computers that had been compromised by the Code Red worm and left in a vulnerable state. It also targets home users’ computers, which are among the most vulnerable. Because of the network traffic generated, Internet Service Providers (ISPs) for home users suffered a negative impact from the worm. Nimda used many means to infect computers, as shown the attached illustration, "Complexity of Nimda Infection Vectors." For example, the worm not only propagates though email attachments and by compromises of vulnerable Internet Information Servers, but it also spreads through shared files on a file server and through web pages containing JavaScript that have been altered on a compromised server.

The algorithm used to spread the worm concentrated for the most part on local networks, so the primary effect of the worm occurred at the "edges" of the Internet. Operators of the backbone of the Internet were not significantly affected; however, they did experience an increase in customer service calls. Callers could not reach the Internet because of the local scanning and email traffic caused by the worm, so they thought the Internet was "down."

Nimda is the first significant worm or virus that attacks both computers that act as servers and those that are desktop computers. A server provides services such as a web site. Code Red exploited the Internet Information Server (IIS), which is a web server. The Melissa virus spread by means of users’ email on desktop computers. Nimda merges the damaging features of both Code Red and Melissa—and more.

The first public report of Nimda infections occurred Tuesday, September 18, 2001, between 8:30 and 9:00 a.m. Within an hour, numerous organizations were telling the CERT/CC that they were paralyzed by the worm. By the end of the day, more than 100,000 computers had been affected.

That same morning, the CERT/CC published initial information about the worm and actions to take against it. We were also in contact with the vendors of anti-virus products and other response organizations to further spread the word of the problem and to develop antidotes. Later that day, we issued more complete information in a CERT advisory (CA-2001-26). The advisory went to a mailing list of more than 150,000 addresses and was published on our web site (www.cert.org). A copy is attached, along with copies of related advisories.

The worm spread so fast that system administrators, users, and vendors did not have time to prepare. Quick response was a challenge because there was no lead time for advance analysis. In contrast, even with Code Red, analysts had a small amount of lead time to examine an early version of the worm before the later, more aggressive version began causing serious damage.

Analysts were also hampered by the lack of source code for Nimda. Source code is the original form of the program, basic code that reveals how the worm works. Thus, it was not possible to determine quickly what the worm did and what it could potentially do. Analysts quickly obtained the binary code, but it is time consuming to decompile this code and analyze the inner workings of the worm. Analysis through decompiling can take hours, days, or even weeks, depending on the complexity of the program.

Current State of Internet Vulnerability

The Nimda worm clearly points out multiple factors that contribute to Internet security problems and pose obstacles to the solutions. They include the vulnerability of technology on the Internet, the nature of intruder activity, the difficulty of fixing vulnerable systems, and the limits of effectiveness of reactive solutions.

Vulnerability of Technology

Last year, the CERT/CC received 1,090 vulnerability reports, more than double the number of the previous year. In the first half of 2001, we have already received 1,151 reports and expect well over 2,000 reports by the end of this year. These vulnerabilities are caused by software designs that do not adequately protect Internet-connected systems and by development practices that do not focus sufficiently on eliminating implementation flaws that result in security problems.

There is little evidence of movement toward improvement in the security of most products; software developers do not devote enough effort to applying lessons learned about the sources of vulnerabilities. We continue to see the same types of vulnerabilities in newer versions of products that we saw in earlier versions. Technology evolves so rapidly that vendors concentrate on time to market, often minimizing that time by placing a low priority on the security of their products. Until customers demand products that are more secure or there are changes in the way legal and liability issues are handled, the situation is unlikely to change.

Additional vulnerabilities come from the difficulty of securely configuring operating systems and applications software packages. These products are often shipped to customers with security features disabled, forcing the technology user to go through the difficult and error-prone process of properly enabling the security features they need. While the current practices allow the user to more quickly use the product and reduces the number of calls the product vendor’s service center might receive when a product is released, it results in many Internet-connected systems that are misconfigured from a security standpoint.

Intruder Activity: The Ease of Exploitation

CERT/CC experience shows that there has been a steady advance in the sophistication and effectiveness of attack technology. Intruders quickly develop exploit scripts for vulnerabilities discovered in products such as IIS. They then use these scripts to compromise computers and, moreover, share these scripts so that more attackers can use them. These scripts are combined with other forms of technology to develop programs that automatically scan the network for vulnerable systems, attack them, compromise them, and use them to spread the attack even further.

These new attack technologies are causing damage more quickly than those created in the past. The Code Red worm spread around the world faster than the so-called Morris worm moved through U.S. computers in 1988, and faster than the Melissa virus in 1999. With the Code Red worm, there were days between first identification and widespread damage. The Nimda worm caused serious damage within an hour of the first report of infection.

In the past, intruders found vulnerable computers by scanning each computer individually, in effect limiting the number of computers that could be compromised in a short period of time. Now intruders use worm technology to achieve exponential growth in the number of computers scanned and compromised. They can now reach tens of thousands of computers in minutes where it once took weeks or months.

This fast exploitation limits the time security experts like those at the CERT/CC have to analyze the problem and warn the Internet community. Likewise, system administrators and users have little time to protect their systems.

Exacerbating the problem is the difficulty of catching the attackers. Today’s Internet protocols make it easy for intruders to disguise their identity and location. Automated attack technology further distances the attacker from the attack. In the great majority of attacks, attackers go unidentified and fear of prosecution offers little deterrent.

Difficulty of Fixing Vulnerable Systems

With an estimated 2,000 (and climbing) vulnerabilities being discovered each year, system and network administrators are in a difficult situation. They are challenged with keeping up with all the systems they have and all the patches released for those systems. Patches can be difficult to apply and might even have unexpected side effects. We have found that, after a vendor releases a security patch, it takes a long time for system administrators to fix all the vulnerable computer systems. It can be months or years before the patches are implemented on 90-95 percent of the vulnerable computers. For example, we still receive reports of outbreaks of the Melissa virus, which exploits vulnerabilities that are more than two years old.

There are a variety of reasons for the delay. The job might be too time-consuming, too complex, or just given too low a priority for the system administration staff to handle. With increased complexity comes the introduction of more vulnerabilities, so solutions do not solve problems for the long term—system maintenance is never-ending. Because many managers do not fully understand the risks, they neither give security a high enough priority nor assign adequate resources. Exacerbating the problem is the fact that the demand for skilled system administrators far exceeds the supply.

Even in an ideal situation, conscientious system administrators cannot adequately protect their computer systems because other system administrators and users, including home users, do not adequately protect their systems. Incident reports to the CERT/CC indicate that many people do not keep their anti-virus software up to date; and they do not apply patches to close vulnerabilities. Computers on the Internet are extremely interdependent. The security of each system on the Internet affects the security of every other system.

Limits of Effectiveness of Reactive Solutions

For the past 13 years, we have relied heavily on the ability of the Internet community as a whole to react quickly enough to security attacks to ensure that damage is minimized and attacks are quickly defeated. Today, however, it is clear that we are reaching the limits of effectiveness of our reactive solutions. While individual response organizations are all working hard to streamline and automate their procedures and are working together to better coordinate activities, a number of factors have combined to limit the effectiveness of reactive solutions.

  • The number of vulnerabilities in commercial off-the-shelf software is now at the level that it is virtually impossible for any but the best resourced organizations to keep up with the vulnerability fixes.
  • The Internet now connects over 109,000,000 computers and continues to grow at a rapid pace. At any point in time, there are hundreds of thousands of connected computers that are vulnerable to one form of attack or another.
  • Attack technology has now advanced to the point where it is easy for attackers to take advantage of these vulnerable machines and harness them together to launch high-powered attacks.
  • Many attacks are now fully automated and spread at nearly the speed of light across the entire Internet community.
  • The attack technology has become increasingly complex and in some cases intentionally stealthy, thus increasing the time it takes to discover and analyze the attack mechanisms in order to produce antidotes.
  • Internet users have become increasingly dependent on the Internet and now use it for many critical applications as well as online business transactions; even relatively short interruptions in service cause significant economic loss and can jeopardize critical services.

These factors, taken together, indicate that we are now at the point where we can expect many attacks to cause significant economic losses and service disruptions within even the best response times that we can realistically hope to achieve. Aggressive, coordinated response will continue to be necessary, but we must also move quickly to put other solutions in place.

Recommended Actions

Working our way out of the vulnerable position we are in requires a multi-pronged approach that helps us deal with the escalating near-term problem while at the same time building stronger foundations for the future. The work that must be done includes achieving these changes:

  • Higher quality information technology products with security mechanisms that are better matched to the knowledge, skills, and abilities of today’s system managers, administrators, and users
  • Expanded research programs that lead to fundamental advances in computer security
  • A larger number of technical specialists who have the skills needed to secure large, complex systems
  • Increased and ongoing awareness and understanding of cyber-security issues, vulnerabilities, and threats by all stakeholders in cyber space

Higher quality products: In today’s Internet environment, a security approach based on "user beware" is unacceptable. The systems are too complex and the attacks too rapid for this approach to work. Fortunately, good software engineering practices can dramatically improve our ability to withstand attacks. The solutions required are a combination of the following:

  • Virus-resistant/virus-proof software – There is nothing intrinsic about digital computers or software that makes them vulnerable to virus attack or infestation. Viruses propagate and infect systems because of design choices that have been made by computer and software designers. Designs that allow the import of executable code, in one form or another, and allow the unconstrained execution of that code on the machine that received it, are the designs that are susceptible to viruses and their effects. Unconstrained execution allows code developers to easily take full advantage of a system’s capabilities, but does so with the side effect of making the system vulnerable to virus attack. To effectively control viruses in the long term, vendors must provide systems and software that constrain the execution of imported code, especially code that comes from unknown or not-trusted sources. Some techniques to do this have been known for decades. Others, such as "sandbox" techniques, have been more recently developed.
  • Reducing implementation errors by at least two orders of magnitude – Most vulnerabilities in products come from software implementation errors. They remain in products, waiting to be discovered, and are fixed only after they are found while in use. Worse, the same flaws continue to be introduced in new products. Vendors need to be proactive, and adopt known, effective software engineering practices that dramatically reduce the number of flaws in software products.
  • High-security default configurations – With the complexity of today’s products, properly configuring systems and networks to use the strongest security built into the products is difficult, even for people with strong technical skills and training. Small mistakes can leave systems vulnerable and put users at risk when connected to the Internet. Vendors can help reduce the impact of security problems by shipping products with "out of the box" configurations that enable security options rather than require the user to enable them. The user can change these "default" configurations if desired, but would have the benefit of starting from a secure base.

Expanded research in information assurance: It is critical to maintain a long-term view and invest in research toward systems and operational techniques that yield networks capable of surviving attacks while protecting sensitive data. In doing so, it is essential to seek fundamental technological solutions and to seek proactive, preventive approaches, not just reactive, curative approaches.

The research agenda should seek new approaches to system security. These approaches should include design and implementation strategies, recovery tactics, strategies to resist attacks, survivability trade-off analysis, and the development of security architectures. Among the activities should be the creation of

  • A unified and integrated framework for all information assurance analysis and design
  • Rigorous methods to assess and manage the risks imposed by threats to information assets
  • Quantitative techniques to determine cost/benefit of risk mitigation strategies
  • Systematic methods and simulation tools to analyze cascade effects of attacks, accidents, and failures across interdependent systems
  • New technologies for resisting attacks and for recognizing and recovering from attacks, accidents, and failures

More technical specialists: The recent government identification and support of cyber-security centers of excellence and the provision of scholarships that support students working on degrees in these universities are steps in the right direction. The current levels of support, however, are far short of what is required to produce the technical specialists we need to secure our systems and networks. These programs should be expanded over the next five years to build the university infrastructure we will need for the long-term development of trained security professionals.

More awareness and training for Internet users: The combination of easy access and user-friendly interfaces have drawn users of all ages and from all walks of life to the Internet. As a result, many users of the Internet have little understanding of Internet technology or the security practices they should adopt. To encourage "safe computing," there are steps we believe the government could take:

  • Support the development of educational material and programs about cyberspace for all users. There is a critical need for education and increased awareness of the security characteristics, threats, opportunities, and appropriate behavior in cyberspace. Because the survivability of systems is dependent on the security of systems at other sites, fixing one’s own systems is not sufficient to ensure those systems will survive attacks. Home users and business users alike need to be educated on how to operate their computers most securely, and consumers need to be educated on how to select the products they buy. Market pressure, in turn, will encourage vendors to release products that are less vulnerable to compromise.
  • In addition, support programs that provide early training in security practices and appropriate use. This training should be integrated into general education about computing. Children should learn early about acceptable and unacceptable behavior when they begin using computers just as they are taught about acceptable and unacceptable behavior when they begin using libraries. Although this recommendation is aimed at elementary and secondary school teachers, they themselves need to be educated by security experts and professional organizations. Parents need be educated as well and should reinforce lessons in security and behavior on computer networks.


Problems such as the Nimda worm will occur again, and attack technology will evolve to support attacks that are even more virulent and damaging. Our current solutions are not keeping pace with the increased strength and speed of attacks; our information infrastructures are at risk. Solutions are not simple, but must be pursued aggressively to allow us to keep our information infrastructures operating at acceptable levels of risk. However, we can make significant progress by making changes in software design and development practices, increasing the number of trained system managers and administrators, improving the knowledge level of users, and increasing research into secure and survivable systems. Additional government support for research, development, and education in computer and network security would have a positive effect on the overall security of the Internet.

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