CVE-1999-0761 in FreeBSD
Summary
by MITRE
Buffer overflow in FreeBSD fts library routines allows local user to modify arbitrary files via the periodic program.
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Analysis
by VulDB Data Team • 02/13/2017
The vulnerability described in CVE-1999-0761 represents a critical buffer overflow flaw within the FreeBSD fts library routines that enables local users to manipulate arbitrary files through the periodic program. This issue stems from improper input validation and memory management within the file tree traversal functionality that FreeBSD employs for various system operations. The fts library routines are fundamental components used for traversing file hierarchies and performing directory operations, making them essential building blocks for numerous system utilities and administrative tools.
The technical implementation of this vulnerability occurs when the periodic program processes certain input parameters that are then passed to the fts library functions without adequate bounds checking. The buffer overflow manifests when user-supplied data exceeds the allocated buffer space within the fts routines, causing memory corruption that can be exploited to overwrite adjacent memory locations. This particular flaw exists in the way the library handles pathnames and directory entries during traversal operations, where insufficient validation allows malicious input to exceed buffer boundaries and potentially overwrite critical program variables or function return addresses.
The operational impact of this vulnerability extends beyond simple file modification capabilities, as it provides a mechanism for privilege escalation and arbitrary code execution within the local system context. Local users who can influence the periodic program's execution or input parameters can leverage this buffer overflow to modify system files, potentially compromising the integrity of the entire operating system. The attack vector is particularly concerning because the periodic program is typically executed with elevated privileges, making successful exploitation capable of granting attackers significant control over the affected FreeBSD system.
This vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and represents a classic example of improper input validation leading to memory corruption. From an ATT&CK framework perspective, this issue maps to privilege escalation techniques through local exploitation and potentially to persistence mechanisms if attackers can manipulate system files. The vulnerability demonstrates how seemingly benign library functions can become critical attack surfaces when proper memory management and input validation are absent. The remediation strategy involves patching the fts library routines to implement proper bounds checking and input validation, ensuring that all user-supplied data is adequately sanitized before processing. System administrators should also consider implementing additional security controls such as mandatory access controls and privilege separation to limit the potential impact of such vulnerabilities. Regular security audits of system libraries and careful monitoring of program execution patterns can help detect and prevent exploitation attempts targeting similar buffer overflow conditions.