CVE-2013-6441 in lxc
Summary
by MITRE
The lxc-sshd template (templates/lxc-sshd.in) in LXC before 1.0.0.beta2 uses read-write permissions when mounting /sbin/init, which allows local users to gain privileges by modifying the init file.
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Analysis
by VulDB Data Team • 12/23/2024
The vulnerability identified as CVE-2013-6441 resides within the Linux Containers (LXC) virtualization framework, specifically affecting versions prior to 1.0.0.beta2. This issue manifests in the lxc-sshd template implementation where the system incorrectly configures file permissions during the mounting of the /sbin/init file. The template's design flaw creates a security risk by granting read-write access to the critical system initialization binary, which is typically protected and should only be accessible with elevated privileges. This misconfiguration represents a fundamental failure in privilege separation and access control mechanisms that are essential for container security.
The technical exploitation of this vulnerability occurs through a local privilege escalation attack vector where malicious users can modify the /sbin/init file while it remains mounted with write permissions. When the init process executes, it will run the modified version, potentially executing arbitrary code with root privileges. This attack leverages the principle of least privilege violation, where the system fails to properly enforce access controls on critical system components. The vulnerability directly maps to CWE-276, which addresses incorrect permissions for critical resources, and demonstrates poor implementation of the principle of least privilege in containerized environments.
The operational impact of this vulnerability extends beyond simple privilege escalation to compromise the entire containerized system. Attackers who gain access to a container with this vulnerability can effectively break out of container isolation boundaries and elevate their privileges to root level on the host system. This creates a severe security risk for multi-tenant environments where multiple users share the same host infrastructure. The vulnerability undermines the core security model of containerization by allowing local users to manipulate system initialization processes, potentially leading to complete system compromise. This type of attack aligns with ATT&CK technique T1068, which covers local privilege escalation through exploitation of system-level vulnerabilities.
Mitigation strategies for CVE-2013-6441 require immediate system updates to LXC versions 1.0.0.beta2 or later where the template properly implements read-only mounting of critical system files. System administrators should also implement additional security controls including regular monitoring for unauthorized modifications to system binaries, enforcement of file integrity checking mechanisms, and proper access control policies for container templates. The fix implemented in later versions addresses the specific issue by ensuring that /sbin/init is mounted with appropriate read-only permissions, preventing modification attacks while maintaining functional integrity. Organizations should also consider implementing container runtime security solutions that can detect and prevent such privilege escalation attempts, as well as conducting regular security audits of container configurations to identify similar permission misconfigurations.