Home > Articles > Security > Network Security

This chapter is from the book

Outsiders versus Insiders: What Is NSM's Focus?

This book is about network security monitoring. I use the term network to emphasize the book's focus on traffic and incidents that occur over wires, radio waves, and other media. This book does not address intruders who steal data by copying it onto a USB memory stick or burning it to a CD-ROM. Although the focus for much of the book is on outsiders gaining unauthorized access, it pertains equally well to insiders who transfer information to remote locations. In fact, once an outsider has local access to an organization, he or she looks very much like an insider. [10]

Should this book (and NSM) pay more attention to insiders? One of the urban myths of the computer security field holds that 80% of all attacks originate from the inside. This "statistic" is quoted by anyone trying to sell a product that focuses on detecting attacks by insiders. An analysis of the most respected source of computer security statistics, the Computer Crime and Security Survey conducted annually by the Computer Security Institute (CSI) and the FBI, sheds some light on the source and interpretation of this figure. [11]

The 2001 CSI/FBI study quoted a commentary by Dr. Eugene Schultz that first appeared in the Information Security Bulletin. Dr. Schultz was asked:

I keep hearing statistics that say that 80 percent of all attacks are from the inside. But then I read about all these Web defacements and distributed denial of service attacks, and it all doesn't add up. Do most attacks really originate from the inside?

Dr. Schultz responded:

There is currently considerable confusion concerning where most attacks originate. Unfortunately, a lot of this confusion comes from the fact that some people keep quoting a 17-year-old FBI statistic that indicated that 80 percent of all attacks originated from the [inside]. . . . Should [we] ignore the insider threat in favor of the outsider threat? On the contrary. The insider threat remains the greatest single source of risk to organizations. Insider attacks generally have far greater negative impact to business interests and operations. Many externally initiated attacks can best be described as ankle-biter attacks launched by script kiddies.

But what I am also saying is that it is important to avoid underestimating the external threat. It is not only growing disproportionately, but is being fueled increasingly by organized crime and motives related to espionage. I urge all security professionals to conduct a first-hand inspection of their organization's firewall logs before making a claim that most attacks come from the inside. Perhaps most successful attacks may come from the inside (especially if an organization's firewalls are well configured and maintained), true, but that is different from saying that most attacks originate from the inside. [12]

Dr. Dorothy Denning, some of whose papers are discussed in Appendix B, confirmed Dr. Shultz's conclusions. Looking at the threat, noted by the 2001 CSI/FBI study as "likely sources of attack," Dr. Denning wrote in 2001:

For the first time, more respondents said that independent hackers were more likely to be the source of an attack than disgruntled or dishonest insiders (81% vs. 76%). Perhaps the notion that insiders account for 80% of incidents no longer bears any truth whatsoever. [13]

The 2002 and 2003 CSI/FBI statistics for "likely sources of attack" continued this trend. At this point, remember that the statistic in play is "likely sources of attack," namely the party that embodies a threat. In addition to disgruntled employees and independent hackers, other "likely sources of attack" counted by the CSI/FBI survey include foreign governments (28% in 2003), foreign corporations (25%), and U.S. competitors (40%).

Disgruntled employees are assumed to be insiders (i.e., people who can launch attacks from inside an organization) by definition. Independent hackers are assumed to not be insiders. But from where do attacks actually originate? What is the vector to the target? The CSI/FBI study asks respondents to rate "internal systems," "remote dial-in," and "Internet" as "frequent points of attack." In 2003, 78% cited the Internet, while only 30% cited internal systems and 18% cited dial-in attacks. In 1999 the Internet was cited at 57% while internal systems rated 51%. These figures fly in the face of the 80% statistic.

A third figure hammers the idea that 80% of all attacks originate from the inside. The CSI/FBI study asks for the origin of incidents involving Web servers. For the past five years, incidents caused by insiders accounted for 7% or less of all Web intrusions. In 2003, outsiders accounted for 53%. About one-quarter of respondents said they "don't know" the origin of their Web incidents, and 18% said "both" the inside and outside participated.

At this point the idea that insiders are to blame should be losing steam. Still, the 80% crowd can find solace in other parts of the 2003 CSI/FBI study. The study asks respondents to rate "types of attack or misuse detected in the last 12 months." In 2003, 80% of participants cited "insider abuse of net access" as an "attack or misuse," while only 36% confirmed "system penetration." "Insider abuse of net access" apparently refers to inappropriate use of the Internet; as a separate statistic, "unauthorized access by insiders" merited a 45% rating.

If the insider advocates want to make their case, they should abandon the 80% statistic and focus on financial losses. The 2003 CSI/FBI study noted "theft of proprietary information" cost respondents over $70 million; "system penetration" cost a measly $2.8 million. One could assume that insiders accounted for this theft, but that might not be the case. The study noted "unauthorized access by insiders" cost respondents only $406,000 in losses. [14]

Regardless of your stance on the outsider versus insider issue, any activity that makes use of the network is a suitable focus for analysis using NSM. Any illicit action that generates a packet becomes an indicator for an NSM operation. One of the keys to devising a suitable NSM strategy for your organization is understanding certain tenets of detection, outlined next.

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.


Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.


If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.


This site is not directed to children under the age of 13.


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020