7.6. Using OpenSCAP with the atomic scan command

The atomic scan command enables users to use OpenSCAP scanning capabilities to scan docker-formatted container images and containers on the system. It is possible to scan for known CVE vulnerabilities or for configuration compliance. Additionaly, users can remediate docker-formatted container images to the specified policy.

atomic scan and OpenSCAP Scanner Image

To install the atomic tool for container management, enter the following command:
# yum install atomic
For more information the atomic installation, see the Prerequisites in the Atomic CLI Reference.
After the atomic tool is installed, you also need a scanner, which is used by the atomic scan command as a back end for scanning images and containers. Red Hat recommends choosing the OpenSCAP scanner bundled in the rhel7/openscap container image in the registry.access.redhat.com image registry:
# atomic install registry.access.redhat.com/rhel7/openscap
The registry.access.redhat.com/rhel7/openscap container image is used as the default scanner by the atomic scan command. It currently supports two scan types targeting Red Hat Enterprise Linux systems. To list supported scan types, enter the following command:
# atomic scan --scanner openscap --list

7.6.1. Scanning Docker-formatted Images and Containers for Vulnerabilities Using atomic scan

To scan the containers and container images, use the atomic scan command in the following form:
# atomic scan [OPTIONS] [ID]
where ID is the ID of the container image or container. To scan all container images or containers, use the --images or --containers directive, respectively. To scan both types, use the --all directive. The list of available command-line options can be obtained using the atomic scan --help command.

Note

For a detailed description of the atomic command usage and containers, see the Product Documentation for Red Hat Enterprise Linux Atomic Host. The Red Hat Customer Portal also provides a guide to the Atomic command line interface (CLI).
The default scan type of the atomic scan command is CVE scan. Use it for checking a target for known security vulnerabilities as defined in the CVE OVAL definitions released by Red Hat.

Warning

The OVAL definitions used by the CVE scan type are bundled in the container image during the build process. Red Hat provides weekly updates of the container image. Always use the latest OpenSCAP container image to ensure the definitions are up to date. To find out version of the installed OpenSCAP container image:
# atomic help registry.access.redhat.com/rhel7/openscap | grep version

Example 7.13. Scanning Red Hat Enterprise Linux 7 Container Images for Known Security Vulnerabilities

The following command scans the Red Hat Enterprise Linux 7 container image for known security vulnerabilities. The --verbose directive provides additional details.
# atomic scan --verbose registry.access.redhat.com/rhel7:latest
docker run -t --rm -v /etc/localtime:/etc/localtime -v /run/atomic/2017-11-01-14-55-37-758180:/scanin -v /var/lib/atomic/openscap/2017-11-01-14-55-37-758180:/scanout:rw,Z -v /etc/oscapd:/etc/oscapd:ro registry.access.redhat.com/rhel7/openscap oscapd-evaluate scan --no-standard-compliance --targets chroots-in-dir:///scanin --output /scanout
WARNING:Can't import the 'docker' package. Container scanning functionality will be disabled.
INFO:Creating tasks directory at '/var/lib/oscapd/tasks' because it didn't exist.
INFO:Creating results directory at '/var/lib/oscapd/results' because it didn't exist.
INFO:Creating results work in progress directory at '/var/lib/oscapd/work_in_progress' because it didn't exist.
INFO:Evaluated EvaluationSpec, exit_code=0.
INFO:Evaluated EvaluationSpec, exit_code=0.
INFO:[100.00%] Scanned target 'chroot:///scanin/db7a70a0414e589d7c8c162712b329d4fc670fa47ddde721250fb9fcdbed9cc2'

registry.access.redhat.com/rhel7:latest (db7a70a0414e589)

registry.access.redhat.com/rhel7:latest passed the scan

Files associated with this scan are in /var/lib/atomic/openscap/2017-11-01-14-55-37-758180.
The following command scans the Red Enterprise Linux 7.2 container image with several known security vulnerabilities:
#atomic scan registry.access.redhat.com/rhel7:7.2
docker run -t --rm -v /etc/localtime:/etc/localtime -v /run/atomic/2017-11-01-14-49-36-614281:/scanin -v /var/lib/atomic/openscap/2017-11-01-14-49-36-614281:/scanout:rw,Z -v /etc/oscapd:/etc/oscapd:ro registry.access.redhat.com/rhel7/openscap oscapd-evaluate scan --no-standard-compliance --targets chroots-in-dir:///scanin --output /scanout

registry.access.redhat.com/rhel7:7.2 (98a88a8b722a718)

The following issues were found:

     RHSA-2017:2832: nss security update (Important)
     Severity: Important
       RHSA URL: https://access.redhat.com/errata/RHSA-2017:2832
       RHSA ID: RHSA-2017:2832-01
       Associated CVEs:
           CVE ID: CVE-2017-7805
           CVE URL: https://access.redhat.com/security/cve/CVE-2017-7805

     RHSA-2017:2016: curl security, bug fix, and enhancement update (Moderate)
     Severity: Moderate
       RHSA URL: https://access.redhat.com/errata/RHSA-2017:2016
       RHSA ID: RHSA-2017:2016-01
       Associated CVEs:
           CVE ID: CVE-2016-7167
           CVE URL: https://access.redhat.com/security/cve/CVE-2016-7167

     RHSA-2017:1931: bash security and bug fix update (Moderate)
     Severity: Moderate
       RHSA URL: https://access.redhat.com/errata/RHSA-2017:1931
       RHSA ID: RHSA-2017:1931-01
       Associated CVEs:
           CVE ID: CVE-2016-0634
           CVE URL: https://access.redhat.com/security/cve/CVE-2016-0634
           CVE ID: CVE-2016-7543
           CVE URL: https://access.redhat.com/security/cve/CVE-2016-7543
           CVE ID: CVE-2016-9401
           CVE URL: https://access.redhat.com/security/cve/CVE-2016-9401

............

Files associated with this scan are in /var/lib/atomic/openscap/2017-11-01-14-49-36-614281.

7.6.2. Scanning and Remediating Configuration Compliance of Docker-formatted Images and Containers Using atomic scan

Scanning for Configuration Compliance of Docker-formatted Images and Containers Using atomic scan

The atomic scan command also supports the configuration_compliance scan. Use this type of scanning to evaluate Red Hat Enterprise Linux-based container images and containers with the SCAP content provided by the SCAP Security Guide (SSG) bundled inside the OpenSCAP container image. This enables scanning against any profile provided by the SCAP Security Guide.
To list the SCAP content provided by the OpenSCAP image for the configuration_compliance scan, enter the following command:
# atomic help registry.access.redhat.com/rhel7/openscap
To verify compliance of the latest Red Hat Enterprise Linux 7 container image with the Defense Information Systems Agency Security Technical Implementation Guide (DISA STIG) policy and generate an HTML report from the scan:
#atomic scan --scan_type configuration_compliance --scanner_args xccdf-id=scap_org.open-scap_cref_ssg-rhel7-xccdf-1.2.xml,profile=xccdf_org.ssgproject.content_profile_stig-rhel7-disa,report registry.access.redhat.com/rhel7:latest
The output of the previous command contains the information about files associated with the scan at the end:
............

Files associated with this scan are in /var/lib/atomic/openscap/2017-11-03-13-35-34-296606.

# tree /var/lib/atomic/openscap/2017-11-03-13-35-34-296606
/var/lib/atomic/openscap/2017-11-03-13-35-34-296606
├── db7a70a0414e589d7c8c162712b329d4fc670fa47ddde721250fb9fcdbed9cc2
│   ├── arf.xml
│   ├── fix.sh
│   ├── json
│   └── report.html
└── environment.json

1 directory, 5 files
The atomic scan generates a subdirectory with all the results and reports from a scan in the /var/lib/atomic/openscap/ directory. The arf.xml file with results is generated on every scanning for configuration compliance. To generate a human-readable HTML report file, add the report suboption to the --scanner_args option.
To generate XCCDF results readable by DISA STIG Viewer, add the stig-viewer suboption to the --scanner_args option. The results are placed in stig.xml. For more information about DISA STIG Viewer, see Section 7.4.7, “Exporting XCCDF Results for the DISA STIG Viewer
The --scanner_args suboptions are separated by the comma character. The specific values for the xccdf-id and profile suboptions, which select an XCCDF component and a profile from the specified datastream file, are taken from the bundled SCAP content in the OpenSCAP image. The datastream file is selected automatically by the OpenSCAP image during scanning based on the target container image or container.

Note

When the xccdf-id suboption of the --scanner_args option is omitted, the scanner searches for a profile in the first XCCDF component of the selected datastream file. For more details about datastream files, see Section 7.2.3, “The Data Stream Format”.

Remediating Configuration Compliance of Docker-formatted Images and Containers Using atomic scan

To remediate docker-formatted container images to the specified policy, add the --remediate option to the atomic scan command when scanning for configuration compliance. The following command builds a new remediated container image compliant with the DISA STIG policy from the Red Hat Enterprise Linux 7 container image:
# atomic scan --remediate --scan_type configuration_compliance --scanner_args profile=xccdf_org.ssgproject.content_profile_stig-rhel7-disa,report registry.access.redhat.com/rhel7:latest

registry.access.redhat.com/rhel7:latest (db7a70a0414e589)

The following issues were found:
............
     Configure Time Service Maxpoll Interval
     Severity: Low
       XCCDF result: fail

     Configure LDAP Client to Use TLS For All Transactions
     Severity: Moderate
       XCCDF result: fail
............
Remediating rule 43/44: 'xccdf_org.ssgproject.content_rule_chronyd_or_ntpd_set_maxpoll'
Remediating rule 44/44: 'xccdf_org.ssgproject.content_rule_ldap_client_start_tls'

Successfully built 9bbc7083760e
Successfully built remediated image 9bbc7083760e from db7a70a0414e589d7c8c162712b329d4fc670fa47ddde721250fb9fcdbed9cc2.


Files associated with this scan are in /var/lib/atomic/openscap/2017-11-06-13-01-42-785000.
The configuration compliance scan is run against the original container image to check its compliance with the DISA STIG policy. Based on the scan results, a fix script containing bash remediations for the failed scan results is generated. The fix script is then applied to the original container image - this is called a remediation. The remediation results in a container image with an altered configuration, which is added as a new layer on top of the original container image. The output of the atomic scan command reports a remediated image ID. To make the image easier to remember, tag it with some name, for example:
#docker tag 9bbc7083760e rhel7_disa_stig

Important

Note that the original container image remains unchanged and only a new layer is created on top of it. The remediation process builds a new container image that contains all the configuration improvements. The content of this layer is defined by the security policy of scanning - in the previous case, the DISA STIG policy. This also means that the remediated container image is no longer signed by Red Hat, which is expected, since it differs from the original container image by containing the remediated layer.