NIST releases guide to security automation protocol

The National Institute of Standards and Technology has published guidelines for using the Security Content Automation Protocol for checking and validating security settings on information technology systems.

SCAP is a NIST specification for expressing and manipulating security data in standardized ways. It's widely used partly because the Office of Management and Budget requires agencies to use products that can use SCAP for checking compliance with Federal Desktop Core Configuration Settings. SCAP's protocols enumerate hardware and software product names and vulnerabilities, including software flaws and configuration issues. They also identify the presence of vulnerabilities and assign severity scores to software flaws.

Guidelines for using the tool are included in Special Publication 800-117, Guide to Adopting and Using the Security Content Automation Protocol (SCAP). The publication also explains how IT product and service vendors can adopt SCAP Version capabilities within their offerings.

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Managing the configurations and security settings of information systems is a challenging job to do manually because the of size, complexity and constant changes in the systems. A wide variety of hardware and software platforms typically are used for many purposes with differing levels of risk in a single environment. The platforms and the threats to them are constantly evolving. Agencies also must conduct continuous monitoring of security configurations and be able to determine the security posture of IT systems at any time.

“All of these tasks are extremely time-consuming and error-prone because there has been no standardized, automated way of performing them,” the special publication states. “Another problem for organizations is the lack of interoperability across security tools; for example, the use of proprietary names for vulnerabilities or platforms creates inconsistencies in reports from multiple tools, which can cause delays in security assessment, decision-making and vulnerability remediation.”

NIST developed SCAP to provide a standardized, automated approach to help agencies overcome these difficulties. SCAP was defined by NIST in SP 800-126 as “a suite of specifications that standardize the format and nomenclature by which security software products communicate software flaw and security configuration information.”

“SCAP can be used to maintain the security of enterprise systems, such as automatically verifying the installation of patches, checking system security configuration settings, and examining systems for signs of compromise,” the new guidelines read. “Individual specifications that comprise SCAP can also be used for forensic activities and other purposes.”

Several organizations created and maintain the SCAP components, including Mitre Corp., the National Security Agency, and the Forum for Incident Response and Security Teams. NIST provides SCAP content such as vulnerability and product enumeration identifiers via the National Vulnerability Database. All database content and the high-level SCAP specification are available free from NIST. Nongovernment organizations also create and make SCAP content available.

The specifications that make up SCAP are:

• Common Vulnerabilities and Exposures, a dictionary of names for publicly known security-related software flaws.
• Common Configuration Enumeration, a dictionary of names for software security configuration issues, such as access control settings and password policy settings.
• Common Platform Enumeration, a naming convention for hardware, operating systems and software.
• Extensible Configuration Checklist Description Format, an Extensible Markup Language specification for structured collections of security configuration rules used by operating systems and applications.
• Open Vulnerability and Assessment Language, an XML specification for exchanging technical details on how to check systems for security-related software flaws, configuration issues and patches.
• Common Vulnerability Scoring System, a method for classifying characteristics of software flaws and assigning severity scores.

According to recommendations that the NIST guidelines offer, organizations should: 

• Use security configuration checklists that are expressed using SCAP. This documents the desired security configuration settings, installed patches and other system security elements in a standardized format. SCAP-expressed checklists are available relevant to specific software, and can be easily customized to meet specific organizational requirements.
• Use SCAP to demonstrate compliance with high-level security requirements. NIST has created mappings between Windows Vista security configuration settings and the high-level security controls in NIST Special Publication (SP) 800-53, which supports Federal Information Security Management Act. The mappings are embedded in SCAP-expressed checklists, which allows SCAP-enabled tools to automatically generate assessment and compliance evidence.
• Use standardized SCAP enumerations — identifiers and product names. The common understanding achieved through the use of standardized enumerations makes it easier to use security tools, share information, and provide guidance in addressing security issues. Organizations should encourage security software vendors to support Common Vulnerabilities and Exposures, Common Configuration Enumeration, and Common Platform Enumeration in their products.
• Use SCAP for vulnerability measurement and scoring. SCAP enables quantitative and repeatable measurement and scoring of software flaw vulnerabilities across systems.
• Use SCAP-validated products. NIST has established a SCAP product validation program, and whenever possible, software developers should make sure that their products have been validated for their ability to assess underlying software configuration settings using SCAP, rather than relying on manual checks or proprietary checking mechanisms.

NIST also encourages software developers and organizations producing security checklists to adopt SCAP. The depth of knowledge makes product vendors particularly helpful in implementing SCAP, and checklist developers can contribute applicable lists to NIST’s National Checklist Program to help ensure that they are available to the broadest possible audience.