Home > Articles > How to Perform a Security Audit - Part 2

How to Perform a Security Audit - Part 2

  • Date: Dec 21, 2001.

Article Description

In her continuing look at what's involved in a security audit, Michelle Johnston explores the technical aspects that come into play – especially those related to e-business systems.

Like this article? We recommend

Designing Network Security

Designing Network Security


This article looks at the technical aspects involved in a security audit of IT systems, particularly those related to e-business systems. The previous article dealt with the business issues involved.

Technical Architecture Requirements

The auditor must ensure that the technical architecture can support the level of security required.

For example, very different security requirements exist for a technical architecture to run an intranet than for one that runs an Internet Web site.

An intranet technical architecture is designed to allow access to internal data and systems only to internal users (usually employees). In such a scenario, a single firewall or proxy server might provide a gateway through which all employees can access the Internet, but no one on the Internet can gain access to internal systems. (This firewall may also restrict the types of content that can be brought back from the Internet by internal users—typically filtering ActiveX controls, downloadable executable files, or sex-related content.) Any mobile employees dialing into the intranet will typically use a VPN mechanism to gain access. It is important for the auditor to check all routes in and out of the intranet to ensure that only authorized users can gain access.

A technical architecture required to support an extranet scenario might employ a DMZ (demilitarized zone) consisting of an internal firewall that provides access to internal systems and data only to internal users (employees), and an external firewall that allows access to certain systems and data to internal users and certain identified external users (usually business partners—for example, Sainsbury's allows key suppliers such as Nestle and Procter and Gamble into its extranet). Intranet users may be logged on transparently to extranet systems, and extranet firewalls may be set up to provide access in this way using IP addresses to identify authorized users (although "spoofing" means that this method is not foolproof).

It is important to check that there are no "back doors" from the extranet into the intranet through which a determined hacker could access internal systems. One of the most common back doors in this scenario is open to the hacker because FTP has not been disabled on the extranet Web server, and the hacker can use FTP to gain access to the intranet system.

Internet-based sites (sites housed at an ISP or at a location where no firewall is used to prevent access) are often overlooked during security audits because they are not housed internally, but they can be the most vulnerable systems because anyone can access them (depending upon the information and data stored within them). Even if there is no restriction on who can or cannot use the Internet site, the site may store personal (or even personalized) information (such as name and address, and credit card information) that must be protected, not only to maintain good customer relationships but also to ensure conformance with data protection legislation.

All three of these types of architectures may require authentication/security controls to be implemented at a number of levels of the architecture. Such measures can be implemented at the network level using firewalls, proxy servers, VPNs, and so on. At the session level, SSL or SET (see http://developer.netscape.com/tech/security/ssl/howitworks.html for information on how the Secure Sockets Layer protocol works) may be used to encrypt all data passing to and from the Web server. At the database level, it is possible to restrict access to individual database servers, databases, tables, columns, rows, views, and stored procedures using database security to users within certain groups or to individual users. It is possible to use database or operating system authentication to identify database users in many cases (for example, using SQL Server). At the operating system level, it is possible to restrict access to individual files, directories, and actions upon files (such as read, write, or execute). At the Web server software level, it is possible to further restrict users and groups when accessing individual Web pages, virtual directories, scripting facilities, and so on.

One of the problems with so many security levels is the inconvenience to the authorized users of having so many levels of security switched on. A compromise must be reached between the amount of inconvenience to the user that is acceptable and the extent to which security is necessary. When data/information is not very sensitive, it may be appropriate to use a single username and password as authentication to identify the user to all systems within a company's extranet, for example. However, when such systems are very sensitive, it is likely that a very different set of usernames and passwords will exist for each one of the extranet systems.

It is important that a security auditor know the implications of using these different methods of security control and ensure that they are being used appropriately. One of the big criticisms of the Microsoft NT/IIS Web server combination is that security possibilities (designed to allow any combination of these security control types to be used) are so complex that many do not bother to use them.

It is also important for the security auditor to recognize the impact upon security of the way the Internet operates. For example, it is often difficult to predict load for a Web site because anyone anywhere in the world theoretically has access to that site at any time. Tales abound in newspapers of sites that collapsed under the strain after a TV show published the URL or an unexpected event brought a surge in visitors (for example, the death of Princess Diana brought down a number of news and florists' sites). Sometimes sites are brought down by denial-of-service attacks also.

The auditor must check that the site's data integrity will remain intact if the site is brought down for any reason. This involves examining how transactions are structured within the database to ensure that when partial transactions exist, either they are rolled back if they lead to inconsistencies or the user has a way of completing the transaction when the site reappears later. For very sensitive transactions, this may require Message Queuing or other transaction-guarantee mechanisms.

It is also sensible within an audit to suggest techniques that could help prevent the site being brought down in this way, such as by careful capacity planning or using redundant hardware. For example, RAID technology can be used to ensure that a disk failure does not bring down the Web server.

Load balancing is another consideration. This may involve a number of Web servers working together and sharing load, or it may simply involve partitioning data into separate databases or database servers, depending upon where the bottleneck is perceived to be. Depending upon the sensitivity of the data, it may make sense anyhow to partition the data in this way so that different business partners are further prevented from accessing information pertaining to their competitors, or so that customers are further prevented from accessing information that only employees should have access to.

For instances in which the site is brought down, it may be prudent for the auditor to suggest improvements to the backup/archiving strategy employed and to investigate more fully the disaster recovery plan.

2. Web Server Configuration | Next Section

Cisco Press Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from Cisco Press 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 Cisco Press 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@ciscopress.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 Cisco Press. 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.ciscopress.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