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Chapter: Information Security : Logical Design

Design of Security Architecture

It promotes strong security measures in its business associates and has established guidelines for the security of its information systems.



ü It promotes strong security measures in its business associates and has established guidelines for the security of its information systems.

ü It has developed two important documents

\endash                 Security Assessment Process


\endash                 Agreed Upon Procedures.


ü Both documents provide specific instructions on the use of the VISA Cardholder Information Security Program.


ü The Security Assessment Process document is a series of recommendations for the detailed examination of an organization’s systems with the eventual goal of integration into the VISA systems.


ü The Agreed upon Procedures document outlines the policies and technologies required for security systems that carry the sensitive card holder information to and from VISA systems.


ü Using the two documents, a security team can develop a sound strategy for the design of good security architecture.


ü The only downside to this approach is the specific focus on systems that can or do integrate with VISA’s systems with the explicit purpose of carrying the aforementioned cardholder information.


Baselining & Best Business Practices


\endash     Baselining and best practices are solid methods for collecting security practices, but provide less detail than a complete methodology


\endash     Possible to gain information by baselining and using best practices and thus work backwards to an effective design


\endash     The Federal Agency Security Practices (FASP) site (fasp.nist.gov) designed to provide best practices for public agencies and adapted easily to private institutions.


\endash     The documents found in this site include specific examples of key policies and planning documents, implementation strategies for key technologies, and position descriptions for key security personnel.


\endash     Of particular value is the section on program management, which includes the following:


              A summary guide: public law, executive orders, and policy documents

              Position description for computer system security officer.



              Position description for information security officer


              Position description for computer specialist.


              Sample of an information technology(IT) security staffing plan for a large service application(LSA)


              Sample of an information technology(IT) security program policy


              Security handbook and standard operating procedures.


              Telecommuting and mobile computer security policy.






\endash                 Hybrid Framework for a Blueprint of an Information Security System


   The framework of security includes philosophical components of the Human Firewall Project, which maintain that people, not technology, are the primary defenders of information assets in an information security program, and are uniquely responsible for their protection.


   The spheres of security are the foundation of the security framework.


   The sphere of use, at the left in fig, explains the ways in which people access information; for example, people read hard copies of documents and can also access information through systems.


   The sphere of protection at the right illustrates that between each layer of the sphere of use there must exist a layer of protection to prevent access to the inner layer from the outer layer.


   Each shaded band is a layer of protection and control.


\endash                 Sphere of Protection


   The “sphere of protection” overlays each of the levels of the “sphere of use” with a layer of security, protecting that layer from direct or indirect use through the next layer


   The people must become a layer of security, a human firewall that protects the information from unauthorized access and use


   Information security is therefore designed and implemented in three layers


–   policies


–   people (education, training, and awareness programs)



–   technology


4.6.7  As illustrated in the sphere of protection, a variety of controls can be used to protect the information.


4.6.8   The items of control shown in the figure are not intended to be comprehensive but rather illustrate individual safeguards that can protect the various systems that are located closer to the center of the sphere.


4.6.9  However, because people can directly access each ring as well as the information at the core of the model, the side of the sphere of protection that attempt to control access by relying on people requires a different approach to security than the side that uses technology.

3 Level of Control


Management Controls


ü     Risk Management


ü     Review of Security Controls


ü     Life Cycle Maintenance


ü     Authorization of Processing (Certification and Accreditation)


ü     System Security Plan


Operational Controls


ü     Personnel Security


ü     Physical Security


ü     Production, Input/Output Controls


ü     Contingency Planning


ü     Hardware and Systems Software


ü     Data Integrity


ü     Documentation


ü     Security Awareness, Training, and Education


ü     Incident Response Capability


Technical Controls


ü     Identification and Authentication


ü     Logical Access Controls


ü     Audit Trails


Management controls


ü It address the design and implementation of the security planning process and security program management.


ü They also address risk management and security control reviews. They further describe the necessity and scope of legal compliance and the maintenance of the entire security life cycle.


Operational controls


ü It deal with the operational functionality of security in the organization. They include management functions and lower level planning, such as disaster recovery and incident response planning.


ü They also address personnel security, physical security, and the protection of production inputs and outputs.


ü They guide the development of education, training and awareness programs for users, administrators, and management. Finally, they address hardware and software systems maintenance and the integrity of data.

Technical controls


1.   It address the tactical and technical issues related to designing and implementing security in the organization, as well as issues related to examining and selecting the technologies appropriate to protecting information.


2.    They address the specifics of technology selection and the acquisition of certain technical components. They also include logical access controls, such as identification, authentication, authorization, and accountability.


3.    They cover cryptography to protect information in storage and transit. Finally, they include the classification of assets and users, to facilitate the authorization levels needed.


Using the three sets of controls, the organization should be able to specify controls to cover the entire spectrum of safeguards, from strategic to tactical, and from managerial to technical.


5.           Defense in Depth


   One of the basic foundations of security architectures is the implementation of security in layers. This layered approach is called defense in depth.


   Defense in depth requires that the organization establish sufficient security controls and safeguards, so that an intruder faces multiple layers of controls.


   These layers of control can be organized into policy, training and education and technology as per the NSTISSC model.


   While policy itself may not prevent attacks, they coupled with other layers and deter attacks.


   Training and Education are similar.


   Technology is also implemented in layers, with detection equipment, all operating behind access control mechanisms.


   Implementing multiple types of technology and thereby preventing the failure of one system from compromising the security of the information is referred to as redundancy.


   Redundancy can be implemented at a number of points throughout the security architecture, such as firewalls, proxy servers, and access controls. The figure shows the use of firewalls and intrusion detection systems(IDS) that use both packet-level rules and data content.



Security Perimeter


ü  A Security Perimeter is the first level of security that protects all internal systems from outside threats.


ü  Unfortunately, the perimeter does not protect against internal attacks from employee threats, or on-site physical threats.


ü  Security perimeters can effectively be implemented as multiple technologies that segregate the protected information from those who would attack it.


ü  Within security perimeters the organization can establish security domains, or areas of trust within which users can freely communicate.


ü  The presence and nature of the security perimeter is an essential element of the overall security framework, and the details of implementing the perimeter make up a great deal of the particulars of the completed security blueprint.


ü  The key components used for planning the perimeter are presented in the following sections on firewalls, DMZs, proxy servers, and intrusion detection systems.


ü           Key Technology Components


   Other key technology components


A firewall is a device that selectively discriminates against information flowing into or out of the organization.


Firewalls are usually placed on the security perimeter, just behind or as part of a gateway router.


Firewalls can be packet filtering, stateful packet filtering, proxy, or application level.


A Firewall can be a single device or a firewall subnet, which consists of multiple firewalls creating a buffer between the outside and inside networks.


The DMZ (demilitarized zone) is a no-man’s land, between the inside and outside networks, where some organizations place Web servers


These servers provide access to organizational web pages, without allowing Web requests to enter the interior networks.

Proxy server- An alternative approach to the strategies of using a firewall subnet or a DMZ is to use a proxy server, or proxy firewall.


When an outside client requests a particular Web page, the proxy server receives the request as if it were the subject of the request, then asks for the same information from the true Web server(acting as a proxy for the requestor), and then responds to the request as a proxy for the true Web server.

For more frequently accessed Web pages, proxy servers can cache or temporarily store the page, and thus are sometimes called cache servers.


Intrusion Detection Systems (IDSs). In an effort to detect unauthorized activity within the inner network, or on individual machines, an organization may wish to implement Intrusion Detection Systems or IDS.


–   IDs come in two versions. Host-based & Network-based IDSs.


Host-based IDSs are usually installed on the machines they protect to monitor the status of various files stored on those machines.

Network-based IDSs look at patterns of network traffic and attempt to detect unusual activity based on previous baselines.


This could include packets coming into the organization’s networks with addresses from machines already within the organization (IP spoofing).


It could also include high volumes of traffic going to outside addresses (as in cases of data theft) or coming into the network (as in a denial of service attack).


–   Both host-and network based IDSs require a database of previous activity.




1             Security Education, Training, and Awareness Program


ü As soon as general security policy exists, policies to implement security education, training and awareness (SETA) program should follow.


ü SETA is a control measure designed to reduce accidental security breaches by employees.


ü Security education and training builds on the general knowledge the employees must possess to do their jobs, familiarizing them with the way to do their jobs securely


4.7.4  The SETA program consists of three elements: security education; security training; and security awareness


4.7.5  The purpose of SETA is to enhance security by:


ü      Improving awareness of the need to protect system resources.


ü      Developing skills and knowledge so computer users can perform their jobs more securely.


ü      Building in-depth knowledge, as needed, to design, implement, or operate security programs for organizations and systems.


Security Education


1      Everyone in an organization needs to be trained and aware of information security, but not every member of the organization needs a formal degree or certificate in information security.


2  A number of universities have formal coursework in information security.


3  For those interested in researching formal information security programs, there are resources available, such as the NSA-identified Centers of Excellence in Information Assurance Education.


Security Training


· It involves providing members of the organization with detailed information and hands-on instruction to prepare them to perform their duties securely.


· Management of information security can develop customized in-house training or outsource the training program.


Security Awareness


ü One of the least frequently implemented, but most beneficial programs is the security awareness program


ü Designed to keep information security at the forefront of users’ minds


ü Need not be complicated or expensive


ü If the program is not actively implemented, employees may begin to “tune out” and risk of employee accidents and failures increases

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