CVE-2001-1145 in FreeBSD
Summary
by MITRE
fts routines in FreeBSD 4.3 and earlier, NetBSD before 1.5.2, and OpenBSD 2.9 and earlier can be forced to change (chdir) into a different directory than intended when the directory above the current directory is moved, which could cause scripts to perform dangerous actions on the wrong directories.
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Analysis
by VulDB Data Team • 02/11/2017
The vulnerability described in CVE-2001-1145 represents a critical directory traversal flaw affecting multiple open source operating systems including FreeBSD, NetBSD, and OpenBSD. This issue specifically impacts the file transfer system (fts) routines that are fundamental components for traversing file hierarchies in Unix-like systems. The flaw stems from improper handling of directory changes during file system traversal operations, creating a condition where the system can be tricked into operating on unintended directories. This type of vulnerability falls under the category of directory traversal attacks and is classified as CWE-22 according to the Common Weakness Enumeration framework. The vulnerability is particularly dangerous because it can be exploited to cause unauthorized access or modification of files in directories that should remain protected.
The technical implementation of this vulnerability occurs when scripts or applications rely on the fts routines to navigate file systems and perform operations. During normal operation, these routines maintain a current working directory context to ensure proper file access. However, when the parent directory of the current working directory is moved or renamed while the fts routine is actively processing, the system can be forced to change into an unintended directory. This misdirection happens because the routines do not properly validate or update their internal directory references when external changes occur to the file system structure. The flaw is particularly insidious because it can be triggered by seemingly benign file system operations that occur concurrently with the fts processing, making it difficult to predict or prevent.
The operational impact of CVE-2001-1145 extends beyond simple directory confusion, potentially enabling attackers to execute dangerous operations on unintended directories. This vulnerability can be exploited to cause unauthorized access to sensitive system files, modify critical configuration data, or even escalate privileges by placing malicious files in system directories. The vulnerability aligns with several techniques documented in the MITRE ATT&CK framework under the category of privilege escalation and persistence. When exploited, this flaw can allow attackers to manipulate the file system in ways that bypass normal security controls, particularly in environments where scripts or applications perform automated file system operations. The risk is compounded in multi-user environments where scripts might be running with elevated privileges and the vulnerability could be leveraged to gain deeper system access.
Mitigation strategies for this vulnerability require immediate system updates and patches from the affected vendors, as the flaw exists in core operating system components. System administrators should prioritize updating to patched versions of FreeBSD 4.4, NetBSD 1.5.2, and OpenBSD 3.0, which contain the necessary fixes for this directory traversal issue. Additionally, implementing proper input validation and directory change monitoring in applications that rely on fts routines can help prevent exploitation. Organizations should also consider implementing file system monitoring to detect unusual directory movement patterns that could indicate attempted exploitation. The vulnerability demonstrates the importance of secure coding practices in system-level components and highlights the need for thorough testing of file system operations under concurrent access conditions. Security teams should conduct comprehensive vulnerability assessments to identify any custom scripts or applications that might be vulnerable to this type of directory traversal attack.