Hardening SUSE Linux Enterprise with OpenSCAP #

SCAP stands for Security Content Automation Protocol. It is a framework of specifications that support automated configuration, vulnerability scanning, and policy compliance evaluation of systems deployed in an organization. It also standardizes how vulnerabilities and security configurations are communicated both to machines and human beings.

OpenSCAP is a collection of open source tools that implement the SCAP framework for Linux. SCAP is maintained by the National Institute of Standards and Technology (NIST) . OpenSCAP received the SCAP 1.2 certification by NIST in 2014.

The OpenSCAP tools, together with the SCAP Security Guide, can be used for auditing your system in an automated way. The SCAP Security Guide implements security guidances recommended by respected authorities. These security guidances are transformed into a machine-readable format which then can be used by OpenSCAP and other tools.

To use the OpenSCAP tools and the SCAP Security Guide for hardening your target system by scanning and remediating vulnerabilities, install the following core packages:

> sudo zypper install openscap openscap-utils scap-security-guide

Note

These packages are dependencies for other optional packages discussed below.

Optionally, install the following packages:

> sudo zypper install scap-workbench scap-workbench-doc ssg-apply

Tip: Security best practice for SCAP Workbench

As a security best practice, avoid installing an application software such as SCAP Workbench on the target system that you are planning to harden. Instead, install SCAP Workbench on a client machine and apply the hardening on the target system, while maintaining an air gap before the target system is connected to a potentially insecure network.

SCAP consists of the following important components which interact with each other.

SUSE ships the SCAP Security Guide (SSG) toolset in the scap-security-guide package. It contains the latest set of security polices for Linux systems. The SCAP Security Guide is maintained upstream in the ComplianceAsCode repository.

After you have installed the package, the SSG security content and the related files are available in your system from the following directories:

The SCAP Security Guide contains multiple profiles. The profiles applicable to SUSE Linux Enterprise are codestream-specific and differ between code 12 and code 15.

They are maintained and hosted at the following repositories:

After the installation of the scap-security-guide package, human-readable versions of the profiles are available in your file system in /usr/share/doc/scap-security-guide/guides.

Alternatively, find the same content online as static HTML pages:

In the online versions, use the drop-down list in the upper-right corner of the page to select one of the available profiles and to view a command-line snippet about how to evaluate the respective profile with OpenSCAP.

6.1 SUSE Linux Enterprise 15 profiles #

  

For code 15, the following profiles are supported by SUSE:

• ANSSI-BP-028 (enhanced)

• ANSSI-BP-028 (high)

• ANSSI-BP-028 (intermediary)

• ANSSI-BP-028 (minimal)

• CIS SUSE SUSE Linux Enterprise 15 Benchmark Level 2 (Workstation)

• CIS SUSE Linux Enterprise 15 Benchmark for Level 1 (Server)

• CIS SUSE Linux Enterprise 15 Benchmark for Level 1 (Workstation)

• CIS SUSE Linux Enterprise 15 Benchmark for Level 2 (Server)

• DISA STIG for SUSE Linux Enterprise 15

• Hardening for Public Cloud Image of SUSE Linux Enterprise Server (SLES) for SAP Applications 15

• Health Insurance Portability and Accountability Act (HIPAA)

• PCI-DSS v4 Control Baseline for SUSE Linux Enterprise 15

• Public Cloud Hardening for SUSE Linux Enterprise 15

• Standard System Security Profile for SUSE Linux Enterprise 15

Figure 1: SCAP Security Guide profiles for SUSE Linux Enterprise 15 #

  

6.2 SUSE Linux Enterprise 12 profiles #

  

For code 12, the following profiles are supported by SUSE:

• ANSSI-BP-028 (enhanced)

• ANSSI-BP-028 (high)

• ANSSI-BP-028 (intermediary)

• ANSSI-BP-028 (minimal)

• CIS SUSE SUSE Linux Enterprise 12 Benchmark Level 2 (Workstation)

• CIS SUSE Linux Enterprise 12 Benchmark for Level 1 (Server)

• CIS SUSE Linux Enterprise 12 Benchmark for Level 1 (Workstation)

• CIS SUSE Linux Enterprise 12 Benchmark for Level 2 (Server)

• DISA STIG for SUSE Linux Enterprise 12

• PCI-DSS v.4 Control Baseline for SUSE Linux Enterprise 12

• Standard System Security Profile for SUSE Linux Enterprise 12

Figure 2: SCAP Security Guide profiles for SUSE Linux Enterprise 12 #

  

The security policy profiles in the SCAP Security Guide can not only be used to scan a target system and to generate reports, but also to automatically apply fixes to the target system (remediation), if possible.

Important: Automatic remediation not always available

Automatic remediation is not offered in case the automatic application of a fix is too dangerous to be enforced in a running target system.

> sudo oscap xccdf eval --remediate1 \
     --profile stig2 \
     --results /tmp/results.xml3 \
     /usr/share/xml/scap/ssg/content/ssg-sle15-ds.xml4

> sudo oscap xccdf generate fix1 \
     --template urn:xccdf:fix:script:sh2 \
     --profile stig3 \
     --output my-remediation-script.sh4 \
     /usr/share/xml/scap/ssg/content/ssg-sle15-ds.xml5

8.4 Remediating a SLE system with Ansible #

  

You can use the Ansible playbooks provided by the SCAP Security Guide to remediate a local system.

The ansible package is available from SUSE Package Hub. Register your SUSE Linux Enterprise system and enable the SUSE Package Hub extension. For SUSE Linux Enterprise 12, you additionally need to enable the Public Cloud module. Then install the package with sudo zypper in ansible.

Example 5: Remediating SLE 15 with Ansible #

  

For example, to remediate your system using the STIG Ansible playbook for SUSE Linux Enterprise 15 provided by the SCAP Security Guide, use the following command.

Warning: System configuration changes

The following command alters the configuration of your system immediately. Make sure to test this thoroughly in a non-production system first.

> sudo ansible-playbook -i "localhost," -c local \
/usr/share/scap-security-guide/ansible/sle15-playbook-stig.yml

After the playbook has finished, you are prompted to log in to your system, which is now compliant to the chosen policy.

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