What is SCAP?
SCAP, the Security Content Automation Protocol, is a suite of specifications maintained by NIST that standardizes how security checklists, vulnerabilities, platforms and assessment results are named, written and reported. Despite the word protocol, nothing about it travels across the network. It is a set of common formats and identifiers, documented in NIST SP 800-126, so that a hardening checklist written once can be evaluated by any SCAP-validated tool and the results from different tools can be compared.
Before SCAP, each scanner vendor wrote checks in its own format, and two tools could report different answers for the same server. SCAP gives them a shared language.
The components of SCAP
SCAP is built from component specifications, and the exact list has changed between SCAP versions. The ones most often named are:
- XCCDF (Extensible Configuration Checklist Description Format): the XML format for a checklist or benchmark, with its rules, profiles and results.
- OVAL (Open Vulnerability and Assessment Language): describes how to test a system's state, such as whether a registry value is set or a package version is installed.
- CVE (Common Vulnerabilities and Exposures): identifiers for publicly known vulnerabilities.
- CVSS (Common Vulnerability Scoring System): severity scores for those vulnerabilities.
- CPE (Common Platform Enumeration): standard names for operating systems, applications and hardware.
- CCE (Common Configuration Enumeration): identifiers for individual configuration settings.
Put together, a checklist written in XCCDF says which rules apply to a platform named by CPE, each rule points to a test written in OVAL, and findings carry standard identifiers (CVE, CCE) and scores (CVSS).
How SCAP scanning works
A team picks SCAP content for the benchmark it must meet, such as a DISA STIG or a CIS Benchmark, chooses a profile within it, and loads it into a SCAP-capable scanner. The scanner evaluates each host rule by rule and produces machine-readable results plus a readable report. Run on a schedule, the same scan catches configuration drift: a server that passed last quarter and fails now because someone changed a setting.
With the open source OpenSCAP tool on a Red Hat Enterprise Linux 9 server, a scan against the STIG profile shipped in the SCAP Security Guide content looks like this:
oscap xccdf eval --profile xccdf_org.ssgproject.content_profile_stig --results web01-results.xml --report web01-report.html /usr/share/xml/scap/ssg/content/ssg-rhel9-ds.xml
Each rule, such as one requiring a minimum password length, returns a result like pass, fail or not applicable, and the report adds an overall score. The DoD's SCAP Compliance Checker (SCC) does the same job for STIG benchmarks on DoD systems, and many commercial vulnerability scanners consume SCAP content as well.
SCAP vs. vulnerability scanning vs. benchmarks
- A benchmark (CIS Benchmark, STIG, vendor baseline) is the list of recommended settings. SCAP is one way to express that list so tools can check it.
- A vulnerability scan looks for known flaws, such as missing patches. A SCAP compliance scan checks configuration against a checklist. Many products do both, and vulnerability checks can themselves be written in OVAL.
- Monitoring protocols such as syslog, SNMP and NetFlow carry events, device status and traffic data. SCAP carries none of that; it describes what a correct configuration looks like and how to test for it.
Why SCAP matters for compliance
Auditors want evidence, not assurances. SCAP results give a timestamped, rule-by-rule record showing whether each host met the required configuration, with standard identifiers an auditor can trace back to the benchmark. Organizations that must meet DoD, federal or industry baselines use SCAP scans to prove compliance across hundreds or thousands of hosts without checking each one by hand. The results are only as good as the content, though: an outdated benchmark or the wrong profile produces a clean report against the wrong standard.
SCAP on the CompTIA Security+ exam
SCAP is part of objective 4.4 on SY0-801, which covers the tools and concepts used for security monitoring and alerting. Look for wording such as "standardized format," "automate compliance checking," "evaluate systems against a published checklist" or "machine-readable benchmark." Common distractors are SNMP, which reports device status, NetFlow, which records traffic metadata, and a generic vulnerability scan, which finds missing patches rather than proving a configuration matches a standard. If the question names XCCDF or OVAL, the answer is SCAP. CVE and CVSS, which you meet in vulnerability management, are components inside SCAP.