CVE-2018-10856 in podman
Summary
by MITRE
It has been discovered that podman before version 0.6.1 does not drop capabilities when executing a container as a non-root user. This results in unnecessary privileges being granted to the container.
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Analysis
by VulDB Data Team • 03/29/2023
The vulnerability identified as CVE-2018-10856 affects podman versions prior to 0.6.1, representing a critical security flaw in container runtime execution. This issue stems from the improper handling of Linux capabilities within the containerization framework, where the software fails to properly restrict privileges even when containers are executed under non-root user contexts. The fundamental problem lies in the violation of privilege separation principles that are essential for container security models, creating potential attack vectors that could be exploited by malicious actors.
The technical flaw manifests through the failure of podman to implement capability dropping mechanisms during container execution. Linux capabilities provide a fine-grained permission system that allows processes to have specific privileges without requiring full root access. When podman does not drop these capabilities, containers retain unnecessary privileges that could be leveraged for privilege escalation attacks. This behavior directly contradicts the principle of least privilege and represents a CWE-250 weakness related to execution with unnecessary privileges. The vulnerability enables containers to maintain capabilities such as CAP_SYS_ADMIN, CAP_NET_ADMIN, or other potentially dangerous privileges that should be stripped when operating under non-root contexts.
The operational impact of this vulnerability extends beyond simple privilege retention, creating significant risks for containerized environments that rely on podman for deployment and management. Attackers could potentially exploit the retained capabilities to access system resources, manipulate network configurations, or escalate privileges within the container environment. This flaw particularly affects organizations using podman in production environments where security isolation is paramount, as it undermines the security boundaries that containers are designed to provide. The vulnerability creates a persistent risk for systems where containers are deployed with elevated privileges, potentially allowing attackers to move laterally within the infrastructure or compromise underlying host systems.
Mitigation strategies for CVE-2018-10856 primarily involve upgrading to podman version 0.6.1 or later, which includes the proper implementation of capability dropping mechanisms. Organizations should also implement additional security controls such as running containers with minimal required capabilities, utilizing user namespaces for further isolation, and implementing comprehensive monitoring for unauthorized privilege usage. The remediation aligns with ATT&CK technique T1068 which focuses on local privilege escalation through improper privilege management. Security teams should conduct thorough vulnerability assessments of existing container deployments to identify any instances where containers might be running with unnecessary privileges, and implement automated patch management processes to ensure timely updates across all podman installations.