Advising users on computer systems technology

November 1992

This CSL Bulletin discusses issues related to sensitive information and clarifies the meaning of "sensitivity" as applied to agency information systems. It draws upon several years of NIST's experience in assisting federal agencies to implement the Computer Security Act of 1987 and the visits to senior agency officials by personnel from NIST, the National Security Agency, and the Office of Management and Budget.

NIST believes that it is more important to provide appropriate protection to agency information technology (IT) systems than to determine whether or not a "sensitive" label should be applied to particular information or IT systems.

Sensitivity and the Computer Security Act of 1987

The Computer Security Act of 1987 (P.L. 100-235) was enacted to create "a means for establishing minimum acceptable security practices" for federal unclassified computer systems. The Act also emphasizes that federal information requires protection against unauthorized modification or destruction, as well as unauthorized disclosure. An improved level of security is obtained by the determination of protection requirements and the selection of cost-effective security controls to meet those requirements.

To distinguish systems covered by P.L. 100-235 from those used to process national security information, the law uses the term "sensitive." Confusion over this term may have led some agencies to focus their limited computer security resources on determining which systems would be labelled "sensitive."

NIST believes that the Computer Security Act did not intend to create two governmentwide categories of information: "sensitive" and "non-sensitive." Likewise, we believe the Act did not create a category of "non-sensitive systems" that could be operated without regard for security. All systems must include security controls that reflect the true importance of the information processed on the system and/or the government investment embodied in the components of the information system.


Many people think that sensitive information only requires protection from unauthorized disclosure. However, the Computer Security Act provides a much broader definition of the term "sensitive" information:

any information, the loss, misuse, or unauthorized access to or modification of which could adversely affect the national interest or the conduct of federal programs, or the privacy to which individuals are entitled under section 552a of title 5, United States Code (the Privacy Act), but which has not been specifically authorized under criteria established by an Executive Order or an Act of Congress to be kept secret in the interest of national defense or foreign policy.

The above definition can be contrasted with the long-standing confidentiality-based information classification system for national security information (i.e., CONFIDENTIAL, SECRET, and TOP SECRET). This system is based only upon the need to protect classified information from unauthorized disclosure; the U.S. Government does not have a similar governmentwide system for unclassified information. No governmentwide schemes exist which are based on the need to protect the integrity or availability of information.

The Computer Security Act did not alter the Freedom of Information Act (FOIA); therefore, an agency's determination of sensitivity under this definition does not change the status of releasability under the FOIA.

Agency Determination of "Sensitive"

Interpretation of the Computer Security Act's definition of sensitive is, ultimately, an agency responsibility. Typically, protecting sensitive information means providing for one or more of the following:

Confidentiality - Disclosure of the information must be restricted to designated parties.

Integrity - The information must be protected from errors or unauthorized modification.

Availability - The information must be available within some given timeframe (i.e., protected against destruction).

Many in the computer security community, including NIST, argue that all non-trivial agency information requires some level of protection along at least one of these dimensions (confidentiality, integrity, and availability).

Agencies should determine what protection is required for each agency IT system and how such protection can best be realized in a cost-effective manner. Information "owners," not system operators, should determine what protection their information requires. The type and amount of protection needed depends on the nature of the information and the environment in which it is processed. The controls to be used will depend on the risk and magnitude of the harm resulting from the loss, misuse, or unauthorized access to or modification of the information contained in the system.

In determining appropriate protection measures, it is important to bear in mind that requirements for the protection of a particular type of information are often provided by statute or agency determination. Information required to be protected under statute includes, for example, privacy information (protected under the Privacy Act), financial information (protected under the Federal Manager's Financial Integrity Act), taxpayer information, and individual census data. In other cases, an agency may determine protection requirements for a specific type of information. For example, some individual agencies have created internal "Limited Official Use" or "For Official Use Only" designations for certain types of unclassified information having confidentiality requirements. In either case, however, the selection of specific security controls is usually left to the agency's or the individual user's discretion.

Risk-Based Selection of Security Controls and Minimum Protective Measures Information owners should use a risk-based approach to determine what harm may result if a system is inadequately protected. The potential for harm as well as consideration of the cost of protective measures must be analyzed together. It makes no sense to spend more on protective measures than the potential for harm if integrity, confidentiality, or availability requirements are not achieved. This approach should provide appropriate protection that is cost-effective for agencies.

As appropriate, the selection of security measures may also be undertaken across-the-board at an agency. This begins by examining the agency's operating environment and the typical minimum protection requirements of the information processed by its IT systems. In many cases, it may then be possible to justify the establishment of minimal security controls for the majority of agency systems. Such an approach can often prove cost-effective and result in basic controls being built into systems as a matter of routine. Procurements may also be simplified as a result, since the same controls are being specified for each purchase.

Perceptions of Protection Requirements

Perceptions of the need to protect particular information can vary markedly. It is important for the owners of information to inform others who may access or process information on their behalf as to necessary protection requirements for the information. For example, if agency elements use a central system for running large applications, the perception of the need to protect the data may vary widely between the application manager and the system operator. However, while individual perceptions may vary, ultimately the risk and the magnitude of potential harm to the organization remain unchanged. This highlights the need for application managers and other "owners" of data to set data protection requirements for those processing or accessing the information. "Owners" requirements to protect information can be more effectively met when complemented by the presence of the agency's computer security policy and computer security training and awareness program. Informing employees of the many ways and needs to protect information can lead to a higher degree of cooperation in meeting protection requirements.


The intent of the Computer Security Act is to assure adequate protection of federal IT systems. NIST believes that all non-trivial agency information requires some degree of protection to provide confidentiality, integrity, or availability. Therefore, agencies must determine the protection requirements for all their information and apply an appropriate level of protection. Agencies should be selecting and implementing appropriate cost-effective security controls for all their systems.


Office of Management and Budget, Appendix III, "Security of Federal Automated Information Systems," to Office of Management and Budget Circular A-130, "Management of Federal Information Resources," December 12, 1985.

National Bureau of Standards, Federal Information Processing Standard Publication 65, Guideline for Automatic Data Processing Risk Analysis, August 1979. Available from the National Technical Information Service (NTIS), 5285 Port Royal Road, Springfield, VA 22161, order number FIPSPUB 65.

NIST Special Publication 500-170, Management Guide to the Protection of Information, October 1989. Available from the Government Printing Office (GPO), Washington, DC 20402, order number SN003-003-02968-8.

NIST Special Publication 500-174, Guide for Selecting Automated Risk Analysis Tools, October 1989. Available from NTIS, 5285 Port Royal Road, Springfield, VA 22161, order number PB90-148784.

NIST Publication List 91, Computer Security Publications, available from CSL Publications, NIST, Technology Building, Room B151, Gaithersburg, MD 20899.