CVE-2011-4099 in libcap
Summary
by MITRE
The capsh program in libcap before 2.22 does not change the current working directory when the --chroot option is specified, which allows local users to bypass the chroot restrictions via unspecified vectors.
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Analysis
by VulDB Data Team • 01/05/2025
The vulnerability identified as CVE-2011-4099 resides within the capsh program component of the libcap library version 2.22 and earlier. This flaw represents a significant security weakness in privilege management and sandboxing mechanisms that could be exploited by local attackers to circumvent intended system protections. The capsh program serves as a shell utility for manipulating capabilities within the Linux security framework, and its improper handling of chroot operations creates a dangerous bypass path for privilege escalation.
The technical flaw manifests when the --chroot option is invoked during program execution. Under normal circumstances, chroot operations should establish a new root directory for the process and change the current working directory to match this new environment. However, the vulnerable implementation fails to perform this critical directory change, leaving the process operating from its original working directory even after the chroot has been applied. This inconsistency creates a potential attack vector where malicious users can access files and resources that should be restricted within the chroot environment.
From an operational perspective, this vulnerability allows local users to bypass chroot restrictions through unspecified vectors that leverage the improper directory handling. The impact extends beyond simple privilege escalation as it enables attackers to potentially access sensitive system files, configuration data, or other resources that should be isolated within the chroot environment. This weakness particularly affects systems that rely on chroot jails for security isolation, such as network services, virtual hosting environments, or sandboxed applications where capability manipulation is required.
The vulnerability maps to CWE-252, which addresses improper handling of security restrictions, and aligns with ATT&CK techniques related to privilege escalation and sandbox evasion. Security researchers have noted that this issue particularly affects Unix-like systems where chroot-based security models are implemented alongside capability-based access controls. The flaw demonstrates a fundamental failure in maintaining consistent security boundaries when transitioning between different execution contexts.
Mitigation strategies should focus on updating to libcap version 2.22 or later where this issue has been resolved. System administrators should also implement additional monitoring for unauthorized chroot operations and capability manipulations. The recommended approach includes verifying that all chroot operations properly enforce directory changes and implementing comprehensive access control policies that do not rely solely on chroot isolation. Regular security audits of privilege management tools and capability-based security mechanisms should be conducted to identify similar implementation flaws that could compromise system integrity.