CVE-2018-1102 in OpenShift Enterprise
Summary
by MITRE
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.
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Analysis
by VulDB Data Team • 02/01/2020
The vulnerability identified as CVE-2018-1102 represents a critical privilege escalation flaw within the source-to-image functionality of Red Hat OpenShift Enterprise 3.x platforms. This issue stems from inadequate path validation mechanisms within the tar extraction process, specifically affecting the ExtractTarStreamFromTarReader function located in the tar/tar.go file. The flaw allows maliciously crafted tar archives to exploit path traversal vulnerabilities during extraction, potentially enabling attackers to write files outside of intended directories and gain elevated privileges within the containerized environment.
The technical implementation of this vulnerability resides in the improper handling of symbolic links and directory paths during tar file decompression. When the source-to-image process extracts tar archives containing specially crafted file paths, the validation logic fails to properly sanitize or restrict file destinations, allowing attackers to manipulate the extraction process. This weakness directly maps to CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. The vulnerability is particularly dangerous in containerized environments where privilege escalation can lead to complete system compromise.
The operational impact of CVE-2018-1102 extends beyond simple privilege escalation, as it undermines the fundamental security model of container orchestration platforms. Attackers can leverage this vulnerability to execute arbitrary code with elevated privileges, potentially gaining access to sensitive data, compromising other containers in the same pod, or even escalating to host-level privileges. The vulnerability affects the core functionality of OpenShift's build process, where source code is automatically transformed into container images, making it a critical threat to continuous integration and deployment pipelines. This weakness aligns with ATT&CK technique T1059, which covers command and script injection, and T1068, which addresses local privilege escalation through exploitation of software vulnerabilities.
Mitigation strategies for CVE-2018-1102 primarily involve applying the official patches released by Red Hat, which include enhanced path validation and sanitization mechanisms within the tar extraction routines. Organizations should immediately update their OpenShift Enterprise 3.x installations to the latest patched versions. Additional protective measures include implementing strict image scanning policies, restricting source-to-image access to trusted users and repositories, and employing container runtime security solutions that monitor for suspicious file extraction patterns. Network segmentation and principle of least privilege access controls should also be enforced to limit the potential impact of successful exploitation attempts. The vulnerability highlights the importance of proper input validation and secure coding practices in container orchestration platforms, particularly when handling untrusted data from external sources.