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This chapter is from the book

This chapter is from the book

Performing Vulnerability Assessments

Managing security means dealing with changing tools, technologies, equipment, and business requirements. Anyone who follows security updates related to viruses, security threats, and other constantly changing aspects of the security landscape understands that managing change and coping with new sources of potential threat or compromise is a never-ending task. Thus, it's entirely reasonable to say that security is as much a matter of regular, rigorous routine as it is a matter of mastering and keeping up with a body of knowledge and skills.

One important aspect of the security routine is sometimes called the "Inverse Golden Rule"—namely, do unto yourself before others can do unto you. In less poetic terms, this means that as new exploits and vulnerabilities become known, it's essential that you foist them on your own systems and networks. This permits you to assess, and if necessary correct, potential vulnerabilities before a more malign attack permits someone else to use them against your organization.

What an attacker seeking illicit entry into a system sees as a probe for weaknesses, you should see as a security scan that can report on potential sources of exposure or vulnerability. By performing regular security scans on your systems and networks—especially on any points of ingress from outside your network, but also on any points of ingress to classified information and services—you can anticipate what attackers might attempt, and forestall such attacks by taking proper pre-emptive measures.

This explains why many types of security software packages and services include vulnerability checks as part of what they do. Such offerings range from single-purpose security scanners designed solely to probe for and report on vulnerabilities, to more complex, all-encompassing security or network management systems that not only look for vulnerabilities but also provide tools and controls to help deal with them when they occur. Whatever type of tool or regimen you use to assess your system and network vulnerabilities, it's essential to perform such checks at regular intervals to assess your overall security posture. Likewise, it's equally essential to make what you might call emergency or spot checks for particular vulnerabilities as they become known to the security community at large.

Many organizations create service relationships with security companies who perform regular scans on their behalf. Other organizations prefer to keep such activity in-house, and authorize their IT staffs to mount "white hat" attacks (as distinguished from the bad guys, known as "black hats") and vulnerability scans at regular intervals and as needed. As long as you implement such scans as part of your regular security routine, and make appropriate changes and updates to take cognizance of possible vulnerabilities, it doesn't matter whether you perform the scan or somebody else does it for you. The important thing is that it be done properly and handled correctly.

Case Study: Acme Industries

Essence of the Case

Here are the essential elements in this case:

  • Analyze the scenario

  • Develop a standard security policy


Acme Industries has retained you to help them develop an in-house security policy. Given a set of company networking, system, and communication requirements, you must first decide which of the many standard security policy documents apply to their situation, and will be required to meet their needs, which may be stated as follows:

  • Acme operates at only a single location, and has contracted with a local telecommunications provider to lease two T-1 connections to access the Internet.

  • Acme's sales force includes four traveling staff who require a secure analog dial-in to upload sales orders and download sensitive bid information to/from Acme's sales department's server.

  • Acme's employees are allowed Internet access only for professional use; no personal email or Web surfing is permitted during working hours, and certain Web sites are always off-limits.

  • Acme seeks to conduct more business online, and is contemplating a relationship with VeriSign to which it wants to outsource e-commerce, collections, and digital certificate services.

  • Acme has no third-party relationships that require it to open its internal networks to third parties.

  • Acme's product line rests on a trade secret formulation for a special bearing lubricant that is highly proprietary and confidential.

Given the following list of security policy documents, explain how each item in the list applies or does not apply to the foregoing list of Acme's requirements. If you must make assumptions to establish (or disprove) relevance of any given document, please state those assumptions as well as your explanation. If any document listed requires or implies inclusion of one or more additional documents, please mention those as well.

The list of potential security policy documents is as follows:

  • Acceptable Encryption Policy

  • Acceptable Use Policy

  • Analog/ISDN Line Policy

  • Antivirus Process

  • Application Service Provider Policy

  • Audit Policy

  • Dial-In Access Policy

  • Information Sensitivity Policy

  • Risk Assessment Policy

  • VPN Security Policy


Each of the items just listed is discussed in a parallel list next, according to the stated analytical and information requirements in the case study.

  • Acceptable Encryption Policy. Although encryption is not specifically mentioned in the Acme requirements as stated, the sales force needs for secure communications and the desire to conduct e-commerce and other secure transactions, as well as to contract for digital certificate services, all require encryption services for proper implementation. Thus, this policy will be an important part of Acme's security policy document collection.

  • Acceptable Use Policy. The third item in the list of Acme requirements clearly touches on an acceptable use policy. This type of document is a nearly universal component of a well-crafted security policy document collection in any case.

  • Analog/ISDN Line Policy. Because the sales force wants to dial in to exchange sales-related information with Acme's sales department server, a policy for use of analog lines is clearly required. What may not be as clear is that a requirement to access servers remotely also implies the need for Dial-in Access Policy, Remote Access Policy, and Server Security Policy documents as well.

  • Antivirus Process. Because Acme will be accessing the Internet, it must be prepared to prevent potential sources of infection or harm from viruses, Trojan horses, and other malefic code. Thus, this document is a key element of its security policy document collection.

  • Application Service Provider Policy. Because Acme intends to conduct business (and obtain services) from VeriSign, the company not only needs this document, but will also require a Third-Party Connection Agreement signed by both parties.

  • Audit Policy. Given the sensitive nature of Acme's proprietary data, and its desire to protect the confidentiality of its bid and sales data, Acme needs an audit policy to monitor access to such information.

  • Dial-In Access Policy. See comments for Analog/ISDN Line Policy, which also implies a requirement for this document in the Acme collection.

  • Information Sensitivity Policy. The foundation of any audit policy is data classification. The Information Sensitivity Policy document describes the classification scheme to be used, and how it is to be applied. Thus, it too is a required element in Acme's security policy document collection.

  • Risk Assessment Policy. Risk assessment is the cornerstone of any security policy. Thus, although the requirement for this document is not explicitly stated in any of the aforementioned Acme requirements, it underlies all of those requirements and enhances their further definition and elaboration.

  • VPN Security Policy. Although the requirements for dial-in access for the Acme sales force don't explicitly specify use of a virtual private network, this type of connection offers greater security than ordinary dial-up connections. Although it may be an assumption that Acme would be interested in using such technology to better secure its remote access, use of this technology (and an accompanying policy) should be discussed with Acme as they develop their security policy and the related document collection. If they opt to use VPN connections, this document should be included in the collection.

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