CVE-2002-1674 in FreeBSD
Summary
by MITRE
procfs on FreeBSD before 4.5 allows local users to cause a denial of service (kernel panic) by removing a file that the fstatfs function refers to.
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Analysis
by VulDB Data Team • 09/06/2019
The vulnerability identified as CVE-2002-1674 represents a critical kernel-level flaw within the FreeBSD operating system's procfs implementation prior to version 4.5. This issue resides in the fundamental file system handling mechanisms that govern process information access through the pseudo-file system interface. The vulnerability specifically targets the interaction between the procfs file system and the fstatfs system call, creating a condition where malicious local users can trigger system instability through seemingly benign file operations. The flaw demonstrates a classic example of improper resource management within kernel space, where the system fails to properly validate file references during critical file system operations.
The technical implementation of this vulnerability exploits a race condition or improper validation within the procfs subsystem when handling file removal operations in conjunction with the fstatfs function. When a local user removes a file that is currently being referenced by the fstatfs system call, the kernel's internal data structures become inconsistent, leading to a kernel panic that results in complete system shutdown. This type of vulnerability falls under the category of improper handling of file system references and can be classified as a CWE-119 Improper Access to Memory or CWE-121 Stack-based Buffer Overflow depending on the specific implementation details. The vulnerability demonstrates how kernel-level file system operations can be exploited to cause system-wide failures through manipulation of reference counting mechanisms.
The operational impact of this vulnerability extends beyond simple denial of service, as it represents a fundamental weakness in the kernel's ability to maintain system stability during concurrent file operations. Local users with minimal privileges can effectively compromise system availability, making this a particularly dangerous flaw in multi-user environments where privilege escalation might be possible. The vulnerability affects systems running FreeBSD versions prior to 4.5, which were widely deployed in server environments, potentially exposing numerous systems to unauthorized denial of service attacks. This weakness directly impacts the availability component of the CIA triad and can be categorized under ATT&CK technique T1499.004 for Network Denial of Service and T1068 for Exploitation for Privilege Escalation when combined with other attack vectors.
Mitigation strategies for CVE-2002-1674 require immediate system updates to FreeBSD version 4.5 or later, which includes patched kernel code that properly validates file references during fstatfs operations. System administrators should implement monitoring for unusual file removal patterns in procfs directories and consider implementing additional kernel security modules or hardening measures. The vulnerability highlights the importance of proper kernel resource management and demonstrates why comprehensive testing of file system operations under concurrent access conditions is essential. Organizations should also consider implementing intrusion detection systems that can monitor for suspicious file removal patterns and ensure that all FreeBSD systems are maintained with current security patches to prevent exploitation of similar kernel-level vulnerabilities.