CVE-2018-1102
Description
A flaw was found in source-to-image function as shipped with Openshift Enterprise 3.x. An improper path validation of tar files in ExtractTarStreamFromTarReader in tar/tar.go leads to privilege escalation.
Statement
Package source-to-image as shipped in Red Hat Software Collections has been rated as Important, because it allows an attacker to get access to the victim's machine, but it requires user interaction.
Mitigation
Customers can turn off the source-to-image (S2I) build strategy to prevent access to the exploitable function. Information about how to disable the source-to-image build strategy is in the product documentation.
* Disabling S2I in OpenShift Enterprise 3.0 - https://docs.openshift.com/enterprise/3.0/admin_guide/securing_builds.html#disabling-a-build-strategy-globally
* Disabling S2I in OpenShift Enterprise 3.1 - https://docs.openshift.com/enterprise/3.1/admin_guide/securing_builds.html#disabling-a-build-strategy-globally
* Disabling S2I in OpenShift Enterprise 3.2 - https://docs.openshift.com/enterprise/3.2/admin_guide/securing_builds.html#disabling-a-build-strategy-globally
* Disabling S2I in OpenShift Enterprise 3.3 - https://access.redhat.com/documentation/en-us/openshift_container_platform/3.3/html/cluster_administration/admin-guide-securing-builds
* Disabling S2I in OpenShift Enterprise 3.4 - https://access.redhat.com/documentation/en-us/openshift_container_platform/3.4/html/cluster_administration/admin-guide-securing-builds
* Disabling S2I in OpenShift Enterprise 3.5 - https://access.redhat.com/documentation/en-us/openshift_container_platform/3.5/html/cluster_administration/admin-guide-securing-builds
* Disabling S2I in OpenShift Enterprise 3.6 - https://access.redhat.com/documentation/en-us/openshift_container_platform/3.6/html/cluster_administration/admin-guide-securing-builds
* Disabling S2I in OpenShift Enterprise 3.7 - https://access.redhat.com/documentation/en-us/openshift_container_platform/3.7/html/cluster_administration/admin-guide-securing-builds
* OpenShift Enterprise 3.8 is not a production version (only for upgrades).
* Disabling S2I in OpenShift Enterprise 3.9 - https://access.redhat.com/documentation/en-us/openshift_container_platform/3.9/html/cluster_administration/admin-guide-securing-builds
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 | 9.9 | 8.8 | N/A |
| Attack Vector | Network | Network | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | Low | Low | N/A |
| User Interaction | None | None | N/A |
| Scope | Changed | Unchanged | N/A |
| Confidentiality | High | High | N/A |
| Integrity Impact | High | High | N/A |
| Availability Impact | High | High | N/A |
Vector
Red Hat: CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
NVD: CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory)
An attacker could provide unexpected values and cause a program crash or arbitrary control of resource allocation, leading to excessive consumption of resources such as memory and CPU.
Confidentiality
Technical Impact: Read Memory; Read Files or Directories
An attacker could read confidential data if they are able to control resource references.
Integrity,Confidentiality,Availability
Technical Impact: Modify Memory; Execute Unauthorized Code or Commands
An attacker could use malicious input to modify data or possibly alter control flow in unexpected ways, including arbitrary command execution.
Acknowledgements
Red Hat would like to thank Michael Hanselmann (hansmi.ch) for reporting this issue.
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