CVE-2015-1334 in LXC
Summary
by MITRE
attach.c in LXC 1.1.2 and earlier uses the proc filesystem in a container, which allows local container users to escape AppArmor or SELinux confinement by mounting a poc filesystem with a crafted (1) AppArmor profile or (2) SELinux label.
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Analysis
by VulDB Data Team • 06/09/2022
The vulnerability identified as CVE-2015-1334 affects LXC containerization software version 1.1.2 and earlier, presenting a critical confinement bypass issue that undermines the security boundaries designed to protect containerized environments. This flaw resides within the attach.c component of LXC, which handles container attachment operations and improperly utilizes the proc filesystem within container contexts. The vulnerability specifically targets the security mechanisms that enforce mandatory access controls through AppArmor and SELinux policies, creating a pathway for privilege escalation and lateral movement within containerized infrastructures.
The technical exploitation of this vulnerability stems from the improper handling of filesystem mounts within containerized environments where local users can leverage crafted AppArmor profiles or SELinux labels to mount proof-of-concept filesystems. When LXC processes these mount operations, it fails to properly validate or restrict the security contexts associated with the mounted filesystems, allowing malicious users to bypass the confinement mechanisms that should prevent access to host resources or other containers. This occurs because the proc filesystem access within containers does not adequately enforce the security policies that would normally restrict such operations, creating an attack surface where container users can manipulate the security context of mounted filesystems.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it fundamentally compromises the security model of containerized environments by allowing local users to escape the isolation boundaries that separate containers from each other and from the host system. Attackers can leverage this flaw to gain elevated privileges within the container, potentially leading to full system compromise if the container has access to sensitive resources or if the host system lacks proper isolation controls. The vulnerability affects organizations using LXC containers for application deployment, development environments, and microservices architectures where container security is paramount. This issue particularly impacts cloud environments and container orchestration platforms that rely on LXC for container management, as it undermines the security guarantees that containerization technologies are designed to provide.
Organizations should immediately upgrade to LXC versions 1.1.3 or later where this vulnerability has been patched, as the fix addresses the improper proc filesystem handling in attach.c by implementing proper validation of mount operations and security context enforcement. Additional mitigations include implementing strict container runtime policies that limit the ability to mount filesystems within containers, deploying enhanced monitoring for suspicious mount operations, and ensuring that AppArmor and SELinux policies are properly configured and enforced at the host level. The vulnerability aligns with CWE-276, which addresses improper privileges, and maps to ATT&CK technique T1068, which covers local privilege escalation through container escape mechanisms. Organizations should also consider implementing container security solutions that provide runtime protection and anomaly detection to identify and prevent exploitation attempts of similar vulnerabilities in their containerized environments.