CVE-2007-3962 in fsplib
Summary
by MITRE
Multiple stack-based buffer overflows in fsplib.c in fsplib before 0.9 might allow remote attackers to execute arbitrary code via (1) a long filename that is not properly handled by the fsp_readdir_native function when MAXNAMLEN is greater than 255, or (2) a long d_name directory (dirent) field in the fsp_readdir function.
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Analysis
by VulDB Data Team • 07/21/2021
The vulnerability described in CVE-2007-3962 represents a critical stack-based buffer overflow in the fsplib library version 0.9 and earlier, specifically within the fsplib.c file. This flaw exists in the handling of directory entries and filename processing functions, making it particularly dangerous for networked file systems and applications that rely on this library for file system operations. The vulnerability affects systems where the MAXNAMLEN constant exceeds 255 characters, creating a scenario where maliciously crafted filenames can trigger memory corruption. The issue stems from inadequate input validation and buffer size checking in the fsp_readdir_native and fsp_readdir functions, which process directory listings and file names without proper bounds checking. These functions are commonly used in file system clients and network file sharing implementations, making the attack surface particularly broad.
The technical exploitation of this vulnerability occurs through two distinct attack vectors that both leverage the same underlying flaw in buffer management. The first vector involves sending a filename that exceeds the maximum allowed length, specifically when MAXNAMLEN is greater than 255, causing the fsp_readdir_native function to write beyond the allocated stack buffer. The second vector targets the d_name directory field within the dirent structure during fsp_readdir function execution, where similarly oversized directory entry names can overflow the stack buffer. Both attack paths result in stack corruption that can be leveraged by remote attackers to execute arbitrary code with the privileges of the affected process. The vulnerability is particularly concerning because it does not require local access to exploit, making it a remote code execution vulnerability that can be triggered over network connections. According to CWE standards, this maps to CWE-121, stack-based buffer overflow, and aligns with ATT&CK technique T1059.007 for execution through command and script interpreters, as successful exploitation can lead to complete system compromise.
The operational impact of CVE-2007-3962 extends beyond simple denial of service to full system compromise, as attackers can potentially execute malicious code with elevated privileges. Systems running affected versions of fsplib are particularly vulnerable when they handle file operations over network protocols such as NFS, SMB, or other file sharing mechanisms that utilize this library. The vulnerability affects a wide range of applications including file servers, network file system clients, and any software that depends on fsplib for directory traversal operations. Attackers can exploit this vulnerability to gain unauthorized access to systems, escalate privileges, and potentially establish persistent backdoors. The memory corruption resulting from these buffer overflows can be particularly dangerous as it may lead to unpredictable behavior, system crashes, or complete system takeover. Organizations using affected software should consider the potential for data breaches, system compromise, and unauthorized access to sensitive information. The vulnerability's remote exploitability means that systems can be compromised without physical access, making it particularly dangerous for publicly accessible file servers and network services. This type of vulnerability is often classified under the MITRE ATT&CK framework as a privilege escalation technique, specifically T1068, and can lead to further exploitation through lateral movement and persistence mechanisms.
Mitigation strategies for CVE-2007-3962 should focus on immediate patching of the fsplib library to version 0.9 or later, which contains the necessary buffer overflow protections. Organizations should also implement network segmentation to limit access to file servers and services that utilize the vulnerable library. Input validation measures should be strengthened at all levels of the application stack, including implementing proper bounds checking for directory entries and filename lengths. System administrators should monitor for unusual directory traversal patterns and implement intrusion detection systems that can identify potential exploitation attempts. Additional protective measures include disabling unnecessary file sharing services, implementing strict access controls, and conducting regular security audits of file system operations. The vulnerability highlights the importance of proper buffer management in system libraries and demonstrates the critical need for thorough code review and security testing of foundational components. Organizations should also consider implementing application whitelisting policies and network monitoring to detect and prevent exploitation attempts. Regular updates to all system components and maintaining current security patches remain essential practices for preventing exploitation of similar vulnerabilities in the future. The incident serves as a reminder of the importance of adhering to secure coding practices and proper input validation to prevent buffer overflow attacks that can lead to complete system compromise.