CVE-2005-4347 in kernel-patch-vserver
Summary
by MITRE
The Linux 2.4 kernel patch in kernel-patch-vserver before 1.9.5.5 and 2.x before 2.3 for Debian GNU/Linux does not correctly set the "chroot barrier" with util-vserver, which allows attackers to access files on the host system that are outside of the vserver.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 07/09/2019
The vulnerability described in CVE-2005-4347 represents a critical security flaw in the Linux kernel's virtualization implementation through the vserver technology. This issue affects specific versions of the kernel-patch-vserver package, namely those before 1.9.5.5 for kernel 2.4 and before 2.3 for Debian GNU/Linux systems. The fundamental problem lies in the improper implementation of the chroot barrier mechanism, which is a critical security feature designed to isolate virtual server environments from the host system. The chroot barrier serves as a protective wall that prevents processes running within a virtual server from accessing files and directories outside their designated boundaries, thereby maintaining the integrity and security of the host system.
The technical flaw manifests in how the kernel patch handles the chroot system call when utilized in conjunction with the util-vserver framework. When an attacker exploits this vulnerability, they can bypass the intended isolation boundaries that separate the virtual server environment from the underlying host system. This misconfiguration allows unauthorized access to host system files that should normally remain inaccessible to processes within the vserver. The vulnerability specifically targets the kernel's handling of file system access controls and path resolution mechanisms, creating a pathway for privilege escalation and information disclosure attacks. The flaw essentially undermines the core security principle of virtualization by enabling lateral movement from the isolated virtual environment to the host system resources.
The operational impact of this vulnerability is severe and far-reaching for organizations utilizing vserver-based virtualization solutions. Attackers who successfully exploit this weakness can gain access to sensitive host system files, potentially including system configuration files, user credentials, authentication databases, and other confidential information stored on the host. This unauthorized access capability extends beyond simple file reading to potentially allow attackers to modify system files, install malicious software, or establish persistent backdoors on the host system. The vulnerability affects the fundamental security model of vserver implementations, making it possible for attackers to compromise the entire host infrastructure from within what should be a secure isolated environment. Organizations running multiple vserver instances face increased risk as a single compromised virtual server could potentially be used as a foothold to access other virtual environments or the host system itself.
Mitigation strategies for CVE-2005-4347 focus primarily on upgrading to patched versions of the kernel-patch-vserver package and util-vserver components. System administrators should immediately update their systems to versions 1.9.5.5 or later for kernel 2.4 and 2.3 or later for Debian GNU/Linux. Additionally, implementing proper access controls and monitoring for unusual file access patterns can help detect potential exploitation attempts. The vulnerability aligns with CWE-276, which addresses improper privilege management, and relates to ATT&CK technique T1059 for command and scripting interpreter usage, as attackers may leverage this privilege escalation to execute malicious commands on the host system. Organizations should also consider implementing additional security controls such as mandatory access controls, file integrity monitoring, and regular security audits to protect against exploitation of similar virtualization-related vulnerabilities.