CVE-2017-1000455 in GuixSD
Summary
by MITRE
GuixSD prior to Git commit 5e66574a128937e7f2fcf146d146225703ccfd5d used POSIX hard links incorrectly, leading the creation of setuid executables in "the store", violating a fundamental security assumption of GNU Guix.
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Analysis
by VulDB Data Team • 12/28/2019
The vulnerability identified as CVE-2017-1000455 affects GuixSD, a functional package manager and operating system built on the GNU Guix package management system. This security flaw emerged from an incorrect implementation of POSIX hard links within the software store mechanism, specifically before the Git commit 5e66574a128937e7f2fcf146d146225703ccfd5d. The issue fundamentally compromised the security model of GNU Guix by allowing unauthorized creation of setuid executables within the system store, thereby undermining core security assumptions that govern the integrity and privilege separation of the package management system.
The technical flaw stems from GuixSD's improper handling of hard links during package installation and store management operations. When creating hard links to files in the store, the system failed to properly validate or enforce the security properties that should prevent the creation of setuid binaries. This incorrect implementation allowed malicious actors to potentially manipulate the package store in ways that would result in setuid executables being created, which violates the fundamental principle that only trusted system components should possess elevated privileges. The vulnerability specifically relates to the improper management of file permissions and access controls during hard link operations, creating a path for privilege escalation attacks.
The operational impact of this vulnerability is significant within the GuixSD ecosystem, as it directly compromises the security model that ensures package integrity and prevents unauthorized privilege escalation. Attackers who could exploit this vulnerability could potentially create malicious setuid binaries within the package store, enabling them to gain elevated privileges on systems running vulnerable versions of GuixSD. This creates a serious risk for users who rely on GNU Guix for package management, as it undermines the trust model that allows users to install packages with confidence that they will not compromise system security. The vulnerability particularly affects systems where users might have access to the package store or where package installation processes are not properly sandboxed.
The security implications extend beyond simple privilege escalation to encompass broader concerns about the integrity of the package management system itself. This flaw demonstrates a critical failure in the security design of the system's store management mechanisms, where the fundamental assumptions about file permissions and access controls were not properly enforced. Organizations and individuals using GuixSD should consider the vulnerability as a potential pathway for attackers to gain elevated privileges and potentially compromise the entire system. The issue aligns with CWE-276, which addresses incorrect permissions for critical resources, and represents a failure in the principle of least privilege enforcement within the system's file access controls. Remediation efforts should focus on proper hard link handling, enforcement of setuid binary restrictions, and ensuring that package store operations maintain the security properties that protect against unauthorized privilege escalation. The fix implemented in the subsequent Git commit addresses the core issue by properly handling POSIX hard links and ensuring that setuid executables cannot be created through improper store operations, thereby restoring the expected security model of the GNU Guix system.