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Internet, Intranet, and Extranet

The Internet is accessed using the TCP/IP. The Hypertext Transfer Protocol (HTTP) is an application-level protocol that is used to transfer the collection of online documents known as the World Wide Web (WWW). This application service and combines the use of client software (browser) that can request information from web servers. Web-based applications can deliver static and dynamic content in the form of text, graphics, sound, and data; they can be used as an interface to corporate applications. Delivery of information via the Web can include the use of either client-side (servlets or applets) or server-side (common gateway interface scripts [CGI]) applications. The ease of implementation and use of the Web enables a variety of content-rich applications.

An intranet uses the same basic principles of the Internet but is designed for internal users. Intranets are web based and can contain internal calendaring, web email, and information designed specifically for the authorized users of the intranet. Extranets are web based but serve a combination of users. Extranets are commonly used as a place for partners (organization and external partners) to exchange information. A simple example of an extranet is one in which a supplier provides access to its partners to place orders, view inventory, and place support requests. The extranet usually sits outside the corporate border router and might be a screened host or might be maintained on a screened subnet.

With the wide use of web technologies, it is important to develop policies and procedures regarding proper use of the Internet, the intranet, and extranets. The ease of access via the Web opens the door to the organization’s network and could allow the download of virus-laden or malicious software. Users in the organization need to be aware of the risks associated with downloading potentially dangerous applets, servlets, and programs. The IT organization should monitor Internet access to ensure that corporate assets (bandwidth, servers, and workstations) are being used in a productive manner.

Risks and Controls Related to Network Infrastructure

The network infrastructure incorporates all of the organization’s data, applications, and communications. The IS auditor must assess the risks associated with the infrastructure and the controls in place to mitigate the risk. It is important to keep in mind that the threats associated with the network are both internal and external; they can include risks from misuse, malicious attack, or natural disaster. The IT organizational controls should mitigate business risk, which is the potential harm or loss in achieving business objectives. The risk-management strategy and risk assessment methodology should address all threats and vulnerabilities and their effect on network assets.

The IT organization should have standards in place for the design and operation of the network architecture. The auditor should identify the following:

  • LAN topology and network design

  • Documented network components' functions and locations (servers, routers, modems, and so on)

  • Network topology that includes interconnections and connections to other public networks

  • Network uses, including protocols, traffic types, and applications

  • Documentation of all groups with access to the network (internal and external)

  • Functions performed by administrators of the network (LAN, security, DBA)

Review of this information enables the IS auditor to make informed decisions with regard to threats to the network and the controls used to mitigate the threats.

Administrative, physical, and technical controls should protect the network and its associated components. The physical controls should protect network hardware and software, permitting physical access to only those individuals who are authorized. When entering restricted areas, individuals with access to sensitive areas should be careful that they do not allow an unauthorized user to follow them in. Known as "piggybacking," this occurs when an unauthorized user follows an authorized user into a restricted area. All hardware devices, software, and manuals should be located in a secure location. Network closets that contain cabling, routers, hubs, and switches should have restricted access. Servers and network components should be locked in racks or should be secured in such a manner that the devices and their components cannot be removed. The network operating manuals and documentation should be secured. All electrical equipment should be protected against the effects of static electricity or power surges (static mats/straps, surge protectors). Network equipment should be equipped with uninterruptible power supplies (UPS), in case of power failure, and facilities should be free of dust, dirt, and water.

The IT organization should have logical controls in place to restrict, identify, and report authorized and unauthorized users of the network. All users should be required to have unique passwords and to change them periodically. Access to applications and data on the network should be based on written authorization and should be granted according to job function (need to know). All login attempts (authorized and unauthorized) should be logged, and the logs should be reviewed regularly. All devices and applications within the network infrastructure should be documented, and the documentation should be updated when changes to hardware, software, configurations, or policies are implemented.

The controls that are implemented on the network should ensure the confidentiality, availability (CIA), and integrity of the network architecture. Confidentiality is the capability to ensure that the necessary level of secrecy is enforced throughout each junction of data processing, to prevent unauthorized disclosure. Integrity ensures accuracy and reliability of data and prevents unauthorized (intentional and unintentional) modification of the data. Availability ensures reliable and timely access to data and network resources for authorized individuals.

As an IS auditor, reviewing the network documentation and logs will provide you with a perspective of the risks associated with the network, but direct observation will provide a more reliable way to determine whether the controls protect the organization. The IS auditor should observe physical security controls and monitor IT resources during daily activities. These results can then be compared against the existing documentation collected to determine adherence.

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