CVE-2014-4043 in C Library
Summary
by MITRE
The posix_spawn_file_actions_addopen function in glibc before 2.20 does not copy its path argument in accordance with the POSIX specification, which allows context-dependent attackers to trigger use-after-free vulnerabilities.
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Analysis
by VulDB Data Team • 06/22/2021
The vulnerability identified as CVE-2014-4043 resides within the glibc library's posix_spawn_file_actions_addopen function, affecting versions prior to 2.20. This flaw represents a critical security issue that undermines the fundamental memory safety mechanisms designed to prevent use-after-free conditions. The vulnerability manifests when the function fails to properly duplicate the path argument as required by the POSIX standard, creating a scenario where memory references become invalid after the original path string is freed or reused. This deviation from established specifications creates exploitable conditions that can be leveraged by malicious actors to execute arbitrary code or cause system instability.
The technical implementation of this vulnerability stems from the improper handling of memory allocation within the posix_spawn_file_actions_addopen function. According to the POSIX standard, when adding open actions to a spawn file actions structure, the function should create an independent copy of the path argument to ensure that the memory reference remains valid throughout the execution lifecycle. However, glibc versions before 2.20 failed to perform this required copy operation, leaving the internal data structure pointing to memory that may be deallocated or overwritten. This behavior directly correlates to CWE-415 which addresses double free vulnerabilities and CWE-416 which covers use-after-free conditions, both of which are fundamental memory safety issues that compromise system integrity.
The operational impact of CVE-2014-4043 extends beyond simple memory corruption, as it provides attackers with a pathway to execute arbitrary code within the context of processes that utilize the vulnerable posix_spawn functionality. Attackers can manipulate the path argument to point to maliciously crafted data structures, potentially leading to privilege escalation or complete system compromise. This vulnerability is particularly dangerous because it operates at the system library level, meaning that any application relying on glibc's posix_spawn functions could be exploited. The context-dependent nature of the vulnerability means that exploitation requires specific conditions related to how applications use the posix_spawn API, but once these conditions are met, the attack surface becomes quite broad.
Mitigation strategies for CVE-2014-4043 primarily focus on upgrading to glibc version 2.20 or later, where the implementation correctly adheres to POSIX specifications. System administrators should prioritize patching affected systems, particularly those running older versions of Linux distributions or embedded systems that rely on vulnerable glibc implementations. Additional protective measures include implementing proper input validation for path arguments when using posix_spawn functions, monitoring for unusual memory access patterns, and applying runtime protections such as stack canaries or address space layout randomization. From an ATT&CK framework perspective, this vulnerability aligns with techniques related to privilege escalation and code injection, as it allows attackers to bypass normal execution boundaries and potentially gain elevated privileges through memory corruption exploits. Organizations should also consider implementing application whitelisting policies and network segmentation to limit the potential impact of successful exploitation attempts.