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Exposure of vSphere's CPI and CSI credentials in Rancher

High severity GitHub Reviewed Published Oct 25, 2024 in rancher/rancher • Updated Nov 5, 2024

Package

gomod github.com/rancher/rancher (Go)

Affected versions

>= 2.9.0, < 2.9.3
>= 2.7.0, < 2.8.9

Patched versions

2.9.3
2.8.9

Description

Impact

A vulnerability has been identified in the way that Rancher stores vSphere's CPI (Cloud Provider Interface) and CSI (Container Storage Interface) credentials used to deploy clusters through the vSphere cloud provider. This issue leads to the vSphere CPI and CSI passwords being stored in a plaintext object inside Rancher. This vulnerability is only applicable to users that deploy clusters in vSphere environments.

The exposed passwords were accessible in the following objects:

  • Can be accessed by users that are cluster members of the provisioned clusters:
    • When provisioning a new cluster with the vSphere cloud provider through Rancher's UI (user interface), Cluster Templates and Terraform on the object provisioning.cattle.io in spec.rkeConfig.chartValues.rancher-vsphere-cpi and spec.rkeConfig.chartValues.rancher-vsphere-csi.
    • On the object rke.cattle.io.rkecontrolplane in spec.chartValues.rancher-vsphere-cpi and spec.chartValues.rancher-vsphere-csi.
  • Can be accessed by users with privileged access to the clusters' infrastructure (host OS):
    • Inside the plan files in the provisioned downstream clusters' filesystems.

Note: if you believe that the vSphere credentials might have been accessed by unauthorized users, it's highly recommended to change them, after updating Rancher to a patched version.

Please consult the associated MITRE ATT&CK - Technique - Credential Access for further information about this category of attack.

Patches

Patched versions include Rancher releases 2.8.9 and 2.9.3.

After updating your environment to one of the patched Rancher's versions, it's mandatory to execute this script that provides an automated way to mitigate any vulnerable leftover vSphere clusters' credentials within Rancher's local cluster. This script doesn't need to be executed in case you are installing a fresh and new environment.

The script will fetch all objects in Rancher's local cluster, loops through them, if the affected vSphere charts are present, then it extracts the username and password parameters into a secret in the fleet-default namespace for both with the appropriate annotation to synchronize them to the downstream clusters. Finally, it updates the cluster's chartValues to reference those secrets rather than existing plaintext values.

The script confirms on write operations, as well as backs up configurations of the cluster objects before operating so rolling back is simple.

To run the script, fetch the kubeconfig for your local cluster and run with KUBECONFIG=/path/to/kubeconfig.yml bash migrate.sh. The script is idempotent and can be run multiple times safely if you want to validate just one at a time.

Notes:

  • The feature flag provisioningprebootstrap must be enabled after updating to one of the patched versions. This feature flag is also mandatory when installing a new cluster.
  • Rancher 2.7 release line is not receiving a backport security patch for this vulnerability. For users running Rancher 2.7 with vSphere provisioning and that are concerned with this security issue, the recommendation is to update Rancher to one of the patched versions by following the standard update procedure based on the 2.7 version that is being used. Refer to the release notes for the proper update process for 2.8.9 and 2.9.3.

Workarounds

Besides only granting access to Rancher to trusted users and not allowing direct access to untrusted users to the clusters' infrastructure, there is no direct workaround for this security issue, except updating Rancher to one of the patched versions.

References

If you have any questions or comments about this advisory:

References

@samjustus samjustus published to rancher/rancher Oct 25, 2024
Published to the GitHub Advisory Database Oct 25, 2024
Reviewed Oct 25, 2024
Last updated Nov 5, 2024

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v4 base metrics

Exploitability Metrics
Attack Vector Network
Attack Complexity Low
Attack Requirements None
Privileges Required Low
User interaction None
Vulnerable System Impact Metrics
Confidentiality High
Integrity Low
Availability Low
Subsequent System Impact Metrics
Confidentiality High
Integrity Low
Availability Low

CVSS v4 base metrics

Exploitability Metrics
Attack Vector: This metric reflects the context by which vulnerability exploitation is possible. This metric value (and consequently the resulting severity) will be larger the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable system. The assumption is that the number of potential attackers for a vulnerability that could be exploited from across a network is larger than the number of potential attackers that could exploit a vulnerability requiring physical access to a device, and therefore warrants a greater severity.
Attack Complexity: This metric captures measurable actions that must be taken by the attacker to actively evade or circumvent existing built-in security-enhancing conditions in order to obtain a working exploit. These are conditions whose primary purpose is to increase security and/or increase exploit engineering complexity. A vulnerability exploitable without a target-specific variable has a lower complexity than a vulnerability that would require non-trivial customization. This metric is meant to capture security mechanisms utilized by the vulnerable system.
Attack Requirements: This metric captures the prerequisite deployment and execution conditions or variables of the vulnerable system that enable the attack. These differ from security-enhancing techniques/technologies (ref Attack Complexity) as the primary purpose of these conditions is not to explicitly mitigate attacks, but rather, emerge naturally as a consequence of the deployment and execution of the vulnerable system.
Privileges Required: This metric describes the level of privileges an attacker must possess prior to successfully exploiting the vulnerability. The method by which the attacker obtains privileged credentials prior to the attack (e.g., free trial accounts), is outside the scope of this metric. Generally, self-service provisioned accounts do not constitute a privilege requirement if the attacker can grant themselves privileges as part of the attack.
User interaction: This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable system. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
Vulnerable System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the VULNERABLE SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the VULNERABLE SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the VULNERABLE SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
Subsequent System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the SUBSEQUENT SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the SUBSEQUENT SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the SUBSEQUENT SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:L/VA:L/SC:H/SI:L/SA:L

Weaknesses

CVE ID

CVE-2022-45157

GHSA ID

GHSA-xj7w-r753-vj8v

Source code

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