This document describes the level of compliance that GKE on VMware has with the CIS Ubuntu Benchmark.
Versions
This document refers to these versions:
| Anthos version | Ubuntu version | CIS Ubuntu Benchmark version | CIS level |
|---|---|---|---|
| 1.7.2 | 18.04 LTS | v2.0.1 | Level 1 Server |
Accessing the benchmark
The CIS Ubuntu Benchmark is available on the CIS website.
Configuration profile
In the CIS Ubuntu Benchmark document, you can read about configuration profiles. The Ubuntu images used by GKE on VMware are hardened to meet the Level 1 - Server profile.
Evaluation on GKE on VMware
We use the following values to specify the status of Ubuntu recommendations in GKE on VMware:
| Status | Description |
|---|---|
| Pass | Complies with a benchmark recommendation. |
| Fail | Does not comply with a benchmark recommendation. |
| Equivalent control | Does not comply with the exact terms in a benchmark recommendation, but other mechanisms in GKE on VMware provide equivalent security controls. |
| Depends on environment | GKE on VMware does not configure items related to a benchmark recommendation. Your configuration determines whether your environment complies with the recommendation. |
Status of GKE on VMware
The Ubuntu images used with GKE on VMware are hardened to meet the CIS Level 1 - Server profile. The following table gives justifications for why GKE on VMware components did not pass certain recommendations.
| # | Recommendation | Scored/Not Scored | Status | Justification | Affected Components |
|---|---|---|---|---|---|
| 1.1.2 | Ensure /tmp is configured | Scored | Fail | Canonical has no plan to modify the cloud image partitions at this time. | All cluster nodes, Admin workstation, Seesaw |
| 1.1.21 | Ensure sticky bit is set on all world-writable directories | Scored | Fail | This could interfere with the functionality of Anthos and its services and is not enabled by default | All cluster nodes, Admin workstation |
| 1.5.1 | Ensure permissions on bootloader config are configured | Scored | Fail | Permissions have been left as default. | All cluster nodes |
| 1.5.2 | Ensure bootloader password is set | Scored | Depends on Environment | No root password is set on Ubuntu cloud images. | All cluster nodes, Admin workstation, Seesaw |
| 1.5.3 | Ensure authentication required for single user mode | Scored | Depends on Environment | No root password is set on Ubuntu cloud images. | All cluster nodes, Admin workstation, Seesaw |
| 1.8.1.2 | Ensure local login warning banner is configured properly | Scored | Equivalent Control | Anthos also applies DISA-STIG hardening to nodes, which updates the warning banner accordingly | All cluster nodes |
| 3.1.2 | Ensure IP forwarding is disabled | Scored | Fail | IP forwarding is necessarily in order for Kubernetes (GKE) to correctly function and route traffic | All cluster nodes, Admin workstation, Seesaw |
| 3.2.7 | Ensure Reverse Path Filtering is enabled | Scored | Depends on Environment | Asynchronous routing and reverse path origination is a requirement for delivering cluster load balancing | Seesaw |
| 3.5.2.5 | Ensure firewall rules exist for all open ports | Not Scored | Depends on Environment | It is recommended that Anthos on VMware be deployed on a private network with appropriate firewall protections. The required firewall rules can be found here. | All cluster nodes, Admin workstation, Seesaw |
| 3.5.4.1.1 | Ensure default deny firewall policy | Scored | Depends on Environment | It is recommended that Anthos on VMware be deployed on a private network with appropriate firewall protections. The required firewall rules can be found here. | All cluster nodes, Admin workstation, Seesaw |
| 3.5.4.1.2 | Ensure loopback traffic is configured | Scored | Depends on Environment | Loopback interface usage is limited given the load balancing functionality used. | Seesaw |
| 3.5.4.2.1 | Ensure IPv6 default deny firewall policy | Scored | Depends on Environment | It is recommended that Anthos on VMware be deployed on a private network with appropriate firewall protections. The required firewall rules can be found here. Additionally, Anthos has no requirement for IPv6 under GA support. | All cluster nodes, Admin workstation, Seesaw |
| 3.5.4.2.2 | Ensure IPv6 loopback traffic is configured | Scored | Depends on Environment | Anthos has no requirement for IPv6 under GA support. | Admin control plane, Seesaw |
| 4.2.1.5 | Ensure rsyslog is configured to send logs to a remote log host | Scored | Depends on Environment | Anthos on VMWare currently collects all journald logs (from system services). These can view these logs under "k8s_node" | All cluster nodes, Admin workstation, Seesaw |
| 4.2.3 | Ensure permissions on all logfiles are configured | Scored | Fail | This specific test is overly restrictive and unrealistic as many services may require a group to write log files. This item may be removed in a future benchmark. | All cluster nodes, Admin workstation, Seesaw |
| 5.2.12 | Ensure SSH PermitUserEnvironment is disabled | Scored | Fail | This setting conflicts with DISA-STAG hardening settings. | All cluster nodes |
| 5.2.13 | Ensure only strong Ciphers are used | Scored | Equivalent Control | The application of DISA-STAG uses an alternative list of supported ciphers which does not 1:1 align with those used by this benchmark | All cluster nodes |
| 5.2.18 | Ensure SSH access is limited | Scored | Depends on Environment | This is not configured by default. This can be configured to meet your specific requirements. | All cluster nodes, Admin workstation, | Seesaw | |
| 5.2.19 | Ensure SSH warning banner is configured | Scored | Equivalent Control | SSH warning banner is modified by the application of DIST-STAG hardening configuration | All cluster nodes |
| 6.1.6 | Ensure permissions on /etc/passwd are configured | Scored | Fail | This specific test is overly restrictive and is being updated by Canonical (link) | All cluster nodes, Admin workstation, Seesaw |
| 6.1.10 | Ensure no world writable files exist | Scored | Fail | Permissions have been left as default. | All cluster nodes |
| 6.1.11 | Ensure no unowned files or directories exist | Scored | Fail | Permissions have been left as default. | All cluster nodes |
| 6.1.12 | Ensure no ungrouped files or directories exist | Scored | Fail | Permissions have been left as default. | All cluster nodes |
| 6.2.10 | Ensure users' dot files are not group or world writable | Scored | Fail | The default settings for Ubuntu permit dot file group permissions due to compatibility | Admin workstation |