FOSSA Logo
X
Compliance
Security
Standards
Configuration Management

XCCDF (Extensible Configuration Checklist Description Format)

A standardized XML-based specification language for writing security checklists, benchmarks, and related documents that enable automated vulnerability management and security compliance testing.

What is XCCDF?

The Extensible Configuration Checklist Description Format (XCCDF) is a standardized XML-based specification language for writing security checklists, benchmarks, and related documents. Developed by the National Institute of Standards and Technology (NIST), XCCDF is a key component of the Security Content Automation Protocol (SCAP) and provides a structured way to express security configuration rules, evaluate compliance with these rules, and report results.

XCCDF enables organizations to automate security compliance testing across various platforms and applications, ensuring consistent security configurations and helping to identify vulnerabilities in system setups.

Core Components of XCCDF

Benchmark

The root element of an XCCDF document that contains the entire security checklist:

<Benchmark id="xccdf_org.example_benchmark_example-benchmark"
           xmlns="http://checklists.nist.gov/xccdf/1.2">
  <status date="2023-06-29">draft</status>
  <title>Example Security Benchmark</title>
  <description>Security guidelines for Example System</description>
  <!-- Additional elements -->
</Benchmark>

Profile

A named set of rules and values tailored for a specific use case or compliance requirement:

<Profile id="xccdf_org.example_profile_high-security">
  <title>High Security Profile</title>
  <description>Configuration settings for high-security environments</description>
  <select idref="xccdf_org.example_rule_require-complex-passwords" selected="true"/>
  <select idref="xccdf_org.example_rule_enable-firewall" selected="true"/>
  <!-- Additional rule selections -->
</Profile>

Rule

A specific security configuration check that can be evaluated automatically:

<Rule id="xccdf_org.example_rule_require-complex-passwords" selected="false">
  <title>Require Complex Passwords</title>
  <description>Ensure that passwords meet complexity requirements</description>
  <rationale>Complex passwords are more resistant to brute-force attacks</rationale>
  <fix>Set the MinimumPasswordLength to 12 in the system configuration</fix>
  <check system="http://oval.mitre.org/XMLSchema/oval-definitions-5">
    <check-content-ref href="example-oval.xml" name="oval:org.example:def:123"/>
  </check>
</Rule>

Value

Variables used in rules that may change based on the environment or profile:

<Value id="xccdf_org.example_value_password-min-length" type="number">
  <title>Minimum Password Length</title>
  <description>The minimum number of characters required for passwords</description>
  <value>12</value>
  <value selector="high-security">16</value>
  <value selector="standard-security">8</value>
</Value>

Group

A logical collection of rules, values, and other groups for organizational purposes:

<Group id="xccdf_org.example_group_account-security">
  <title>Account Security</title>
  <description>Rules related to account and authentication security</description>
  <!-- Rules related to account security -->
</Group>

XCCDF in the Software Supply Chain

Configuration Security

XCCDF helps ensure that software components are deployed with secure configurations:

  • Default Configuration Validation: Verifying that default software configurations meet security requirements
  • Third-Party Component Settings: Ensuring that integrated components and dependencies are configured securely
  • Runtime Environment Checks: Validating that the operating environment for software is hardened appropriately

Compliance Automation

XCCDF enables automated verification of compliance with security policies and standards:

  • Continuous Compliance Checking: Regular automated assessment of configuration compliance
  • DevSecOps Integration: Building compliance checks into CI/CD pipelines
  • Infrastructure as Code Validation: Verifying secure configurations in infrastructure definitions

Security Posture Management

Organizations use XCCDF to maintain and improve their security posture:

  • Baseline Configuration: Establishing a secure baseline for systems and applications
  • Drift Detection: Identifying when configurations deviate from the secure baseline
  • Remediation Guidance: Providing standardized instructions for fixing security issues

XCCDF in Security Standards and Frameworks

NIST Security Content

NIST publishes XCCDF-based security content for various platforms:

  • NIST SP 800-53 Controls: Security controls mapped to XCCDF checks
  • NIST National Checklist Program: Repository of security configuration checklists

CIS Benchmarks

The Center for Internet Security (CIS) provides XCCDF-formatted benchmarks for:

  • Operating Systems: Windows, Linux, macOS, etc.
  • Cloud Platforms: AWS, Azure, Google Cloud
  • Applications: Databases, web servers, containerization platforms

DISA STIGs

The Defense Information Systems Agency (DISA) Security Technical Implementation Guides (STIGs) are available in XCCDF format for:

  • Military Systems: Specialized configurations for defense systems
  • Standard Software: Common operating systems and applications used in defense contexts
  • Network Devices: Routers, switches, and other network infrastructure

How XCCDF Works with Other SCAP Components

OVAL (Open Vulnerability and Assessment Language)

XCCDF rules often reference OVAL definitions for the actual technical checks:

<check system="http://oval.mitre.org/XMLSchema/oval-definitions-5">
  <check-content-ref href="oval-definitions.xml" name="oval:org.example:def:123"/>
</check>

CPE (Common Platform Enumeration)

XCCDF can specify which platforms a benchmark applies to using CPE identifiers:

<platform idref="cpe:/o:microsoft:windows_server:2019"/>

CCE (Common Configuration Enumeration)

Rules can reference CCE identifiers for specific configuration issues:

<Rule id="xccdf_org.example_rule_require-complex-passwords" selected="false">
  <ident system="https://nvd.nist.gov/cce/index.cfm">CCE-27345-6</ident>
  <!-- Other rule content -->
</Rule>

CVSS (Common Vulnerability Scoring System)

XCCDF can incorporate CVSS scores to prioritize security issues:

<Rule id="xccdf_org.example_rule_fix-critical-vulnerability" severity="high">
  <metadata>
    <cvss:base>9.8</cvss:base>
    <cvss:vector>AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H</cvss:vector>
  </metadata>
  <!-- Other rule content -->
</Rule>

Implementing XCCDF in Security Workflows

Authoring XCCDF Content

Tools for creating XCCDF documents include:

  • SCAP Workbench: GUI tool for creating and editing SCAP content
  • OpenSCAP: Command-line utilities for managing SCAP content
  • ComplianceAsCode: Open-source project for building compliance content

Evaluating with XCCDF

The evaluation process typically involves:

  1. Selecting a Benchmark: Choosing the appropriate security checklist
  2. Choosing a Profile: Selecting the security profile that matches requirements
  3. Running an Assessment: Executing the checks against target systems
  4. Reviewing Results: Analyzing compliance status and failures
  5. Remediation: Implementing fixes for non-compliant settings

Example XCCDF Assessment Command

# Using OpenSCAP to evaluate a system against the CIS Benchmark
oscap xccdf eval --profile xccdf_org.cisecurity_profile_Level_1_Server \
                 --results results.xml \
                 --report report.html \
                 CIS_Benchmark.xml

XCCDF Results and Reporting

Results Format

XCCDF evaluation results are also XML-formatted:

<TestResult id="xccdf_org.example_testresult_1" start-time="2023-06-29T10:15:00Z" end-time="2023-06-29T10:20:00Z">
  <rule-result idref="xccdf_org.example_rule_require-complex-passwords">
    <result>pass</result>
  </rule-result>
  <rule-result idref="xccdf_org.example_rule_enable-firewall">
    <result>fail</result>
    <message>Firewall service is not running</message>
  </rule-result>
  <!-- Additional rule results -->
</TestResult>

Common Result Types

  • pass: The target system complies with the rule
  • fail: The target system does not comply with the rule
  • error: An error occurred while checking the rule
  • unknown: The rule checking system couldn't determine compliance
  • notapplicable: The rule doesn't apply to the target system
  • notchecked: The rule was not evaluated
  • informational: The rule provides information but doesn't check compliance
  • fixed: A remediation was applied, and the system now complies

Reporting and Integration

XCCDF results can be:

  • Transformed to HTML/PDF: Human-readable compliance reports
  • Integrated with GRC Platforms: Governance, Risk, and Compliance systems
  • Stored for Trend Analysis: Tracking compliance improvements over time
  • Exported to Dashboards: Visualizing compliance status across the organization

Advantages of XCCDF

  • Standardization: Common format understood by multiple security tools
  • Portability: XCCDF content works across various platforms and vendors
  • Automation: Enables automated checks rather than manual inspection
  • Scalability: Same benchmarks can be applied to thousands of systems
  • Customization: Profiles allow tailoring security requirements to different contexts
  • Separation of Concerns: Distinct separation between policy (what to check) and mechanism (how to check)

Challenges and Limitations

  • Complexity: Creating XCCDF content requires specialized knowledge
  • Maintenance: Security benchmarks need regular updates as technologies evolve
  • Technical Depth: Some security checks require complex OVAL definitions
  • Performance Impact: Running comprehensive benchmarks can impact system performance
  • False Positives/Negatives: Automated checks may miss context or report false issues