Bringing order and security to the patchwork quilt of computing environments in a large organization can be a daunting task. Software tools and technical specifications that allow security information to be shared between information systems—the Security Content Automation Protocol (SCAP)—can save time and improve security. The National Institute of Standards and Technology (NIST) recently released four new publications that detail specifications to be used by the latest version of SCAP.
"A primary goal of automated security in a large organization's computer environment is to make sure everything is configured securely as required by management, and that all patches are applied to eliminate known vulnerabilities," said computer scientist David Waltermire. SCAP-enabled tools can scan computer systems to reveal software vulnerabilities and security configuration problems to be corrected.
SCAP relies on a fundamental component called Common Platform Enumeration (CPE), which is a standardized method of describing and identifying classes of applications, operating systems and hardware devices in an organization's computer systems. A new version of CPE has been released—version 2.3—and the four new NIST Interagency Reports (NISTIRs) provide specifications for this version, which will be used with the new SCAP version.
For SCAP to work, CPE needs to have a unique name to identify all of the same types of products. For example, without CPE, different terms, such as "Windows XP" and "Win XP," typically are used to refer to a single type of product, which can cause confusion and waste resources. CPE provides a single standardized unique name that covers all of these variants. NISTIR 7695 defines and explains the naming specification for CPE version 2.3.
Once a unique name is defined, CPE needs to compare names to determine whether they refer to some or all of the same products or platforms. For example, a product may have a unique name, but as in the Windows XP example, there may be subsets such as "Service Pack 1" or "Service Pack 2" that may further distinguish types of products. NISTIR 7696 provides the CPE name matching specification, which defines procedures for comparing two CPE names.
A dictionary specification for CPE is defined in NISTIR 7697, which includes the semantics of its data model and the rules associated with the CPE dictionary creation and management. NIST hosts the official CPE dictionary at http://nvd.nist.gov/cpe.cfm so organizations can search for and find identifier names.
With the naming, name matching and dictionary specifications defined, researchers moved to language specifications. NISTIR 7698 provides the applicability language specification, which allows construction of logical expressions built from CPE names. These expressions can be used by SCAP to identify more complex vulnerability and configuration situations, such as a problem that only exists when two applications are running together or an application is running on particular computing platforms. A real-life example is writing an applicability language expression that tells SCAP to search for situations in which Adobe Flash player version 10.3 or earlier is running on Mac OSX, Linux, Sun Solaris or Microsoft Windows.
A new publication announcing SCAP Version 1.2 is expected to be published soon. For more information on SCAP and other security automation projects, see scap.nist.gov.