CVE-2013-4237 in C Library
Summary
by MITRE
sysdeps/posix/readdir_r.c in the GNU C Library (aka glibc or libc6) 2.18 and earlier allows context-dependent attackers to cause a denial of service (out-of-bounds write and crash) or possibly execute arbitrary code via a crafted (1) NTFS or (2) CIFS image.
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Analysis
by VulDB Data Team • 05/21/2021
The vulnerability identified as CVE-2013-4237 resides within the GNU C Library's implementation of directory reading functions, specifically in the sysdeps/posix/readdir_r.c component. This flaw affects glibc versions 2.18 and earlier, representing a critical security issue that can be exploited through crafted filesystem images. The vulnerability manifests when the library processes NTFS or CIFS filesystem images, creating a scenario where maliciously constructed filesystem metadata can trigger unintended behavior in the underlying system calls.
The technical nature of this vulnerability stems from improper bounds checking within the readdir_r function implementation, which is designed to read directory entries in a thread-safe manner. When processing malformed NTFS or CIFS images, the library fails to properly validate the size and structure of directory entries, leading to out-of-bounds memory writes. This flaw operates at the system call interface level, making it particularly dangerous as it can be triggered through standard POSIX directory traversal operations that applications commonly use. The vulnerability aligns with CWE-121, which addresses stack-based buffer overflow conditions, and CWE-787, which covers out-of-bounds write vulnerabilities.
The operational impact of this vulnerability extends beyond simple denial of service to potentially enable arbitrary code execution, making it a severe threat to system integrity. Attackers can craft malicious filesystem images that, when processed by applications linked against vulnerable glibc versions, will trigger the out-of-bounds write condition. This can result in system crashes, application instability, or more critically, provide attackers with opportunities to execute code with the privileges of the affected process. The context-dependent nature of the attack means that exploitation requires specific conditions involving the use of NTFS or CIFS filesystems, but the potential for remote code execution through applications that traverse these filesystems makes this vulnerability particularly concerning in networked environments.
Mitigation strategies for CVE-2013-4237 primarily focus on updating to patched versions of glibc, with version 2.19 and later containing the necessary fixes. System administrators should prioritize patching all affected systems, particularly those handling NTFS or CIFS filesystems, as these represent the primary attack vectors. Additionally, implementing proper input validation and sanitization within applications that process filesystem metadata can provide defense-in-depth measures. Network segmentation and access controls should be enforced to limit exposure, while monitoring systems should be configured to detect unusual directory traversal patterns that might indicate exploitation attempts. The vulnerability demonstrates the importance of robust bounds checking in system libraries and highlights the need for comprehensive security testing of core operating system components. Organizations should also consider implementing the principle of least privilege for applications that interact with potentially malicious filesystem images, reducing the potential impact of successful exploitation attempts.