CVE-2006-4243 in Linux
Summary
by MITRE
linux vserver 2.6 before 2.6.17 suffers from privilege escalation in remount code.
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Analysis
by VulDB Data Team • 02/05/2024
The vulnerability identified as CVE-2006-4243 affects the linux vserver implementation in kernel versions prior to 2.6.17, specifically targeting a privilege escalation flaw within the remount code functionality. This issue represents a critical security weakness that allows unprivileged users to gain elevated privileges within the vserver environment, undermining the fundamental security isolation that vserver technology is designed to provide. The vulnerability stems from improper handling of filesystem remount operations, where the kernel fails to properly validate user permissions and access controls during these critical operations.
The technical flaw manifests in the kernel's remount implementation where insufficient input validation and privilege checks exist when processing filesystem remount requests. When a user attempts to remount a filesystem, the kernel code does not adequately verify whether the requesting user possesses the necessary privileges to perform such operations. This oversight creates a pathway for privilege escalation where malicious users can manipulate the remount process to execute code with elevated privileges, effectively bypassing the security boundaries that vserver establishes between different virtual environments. The vulnerability specifically affects the vserver subsystem which provides container-like virtualization capabilities for linux systems, making it particularly dangerous in multi-tenant environments.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it fundamentally compromises the security model of vserver implementations. Attackers can leverage this flaw to gain root access within virtual server environments, potentially allowing them to access sensitive data, modify system configurations, or establish persistent backdoors. The vulnerability is particularly concerning in cloud computing and hosting environments where multiple users share the same physical hardware through vserver technology. The privilege escalation occurs during normal system operations, making detection difficult and increasing the potential for undetected compromise. This weakness directly violates the principle of least privilege and can lead to complete system compromise when exploited in conjunction with other vulnerabilities.
Mitigation strategies for CVE-2006-4243 primarily involve upgrading to kernel versions 2.6.17 or later where the vulnerability has been addressed through proper privilege validation in the remount code. System administrators should also implement additional security controls such as restricting user access to filesystem remount operations, monitoring for unusual remount activities, and ensuring proper user privilege management. The vulnerability aligns with CWE-276, which addresses improper privilege management, and relates to ATT&CK technique T1068, which covers exploit for privilege escalation. Organizations should conduct thorough security assessments of their vserver implementations, review access controls, and implement network segmentation to limit the potential impact of such privilege escalation attacks. Regular kernel updates and security patch management remain the most effective defense against this type of vulnerability.