Security Categorization and Control Selection for National Security Systems: Version 2 [open pdf - 1MB]
"This Instruction serves as a companion document to NIST SP 800-53 [National Institute of Standards and Technology Special Publication 800-53] for organizations that employ NSS [National Security Systems]. It establishes the processes for categorizing NSS and the information they process and for appropriately selecting security controls for NSS from NIST SP 800-53. This Instruction applies to all components of NSS. For NSS, where differences between the NIST documentation and this Instruction occur, this Instruction is authoritative. The controls contained within NIST SP 800-53, Appendices F and G, are directly applicable to the national security community. However, the special nature of NSS results in some variance from the non-NSS sector with respect to the process for information and information system categorization. This Instruction, therefore, provides the processes for categorizing NSS and the information they process and for selecting security controls to provide appropriate protections for NSS. "
Committee on National Security Systems No. 1253; CNSSI No. 1253
Committee on National Security Systems: http://www.cnss.gov/