CVE-2020-8566
Description
A flaw was found in kubernetes. If the logging level is to at least 4, and Ceph RBD is configured as a storage provisioner, then Ceph RBD admin secrets can be written to logs. This occurs in kube-controller-manager's logs during provisioning of Ceph RBD persistent claims.
Statement
OpenShift Container Platform 4 does not support Ceph RBD persistent volumes, however the vulnerable code is included.
Mitigation
OCP Clusters not using Ceph RBD volumes are not vulnerable to this issue. For clusters using Ceph RBD volumes, this can be mitigated by ensuring the logging level is below 4 and protecting unauthorized access to cluster logs.
For OCP, the logging level for core components can be configured using operators, e.g. for kube-controller-manager:
https://docs.openshift.com/container-platform/latest/rest_api/operator_apis/kubecontrollermanager-operator-openshift-io-v1.html#specification
In OCP, a logging level of "Debug" is equivalent to 4:
https://github.com/openshift/api/blob/master/operator/v1/types.go#L96
The default logging level is "Normal", which is equivalent to 2. Clusters running with the default level are not vulnerable to this issue.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.3 | 5.5 | N/A |
| Attack Vector | Network | Local | N/A |
| Attack Complexity | High | Low | N/A |
| Privileges Required | Low | Low | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | High | High | N/A |
| Integrity Impact | None | None | N/A |
| Availability Impact | None | None | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
NVD: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Understanding the Weakness (CWE)
Integrity,Confidentiality,Availability,Non-Repudiation
Technical Impact: Modify Application Data; Hide Activities; Execute Unauthorized Code or Commands
Interpretation of the log files may be hindered or misdirected if an attacker can supply data to the application that is subsequently logged verbatim. In the most benign case, an attacker may be able to insert false entries into the log file by providing the application with input that includes appropriate characters. Forged or otherwise corrupted log files can be used to cover an attacker's tracks, possibly by skewing statistics, or even to implicate another party in the commission of a malicious act. If the log file is processed automatically, the attacker can render the file unusable by corrupting the format of the file or injecting unexpected characters. An attacker may inject code or other commands into the log file and take advantage of a vulnerability in the log processing utility.
Acknowledgements
Red Hat would like to thank the Kubernetes Product Security Committee for reporting this issue. Upstream acknowledges Kaizhe Huang (derek0405) as the original reporter.
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