CVE-2007-0895 in Solaris
Summary
by MITRE
Race condition in recursive directory deletion with the (1) -r or (2) -R option in rm in Solaris 8 through 10 before 20070208 allows local users to delete files and directories as the user running rm by moving a low-level directory to a higher level as it is being deleted, which causes rm to chdir to a ".." directory that is higher than expected, possibly up to the root file system, a related issue to CVE-2002-0435.
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Analysis
by VulDB Data Team • 08/23/2019
The vulnerability described in CVE-2007-0895 represents a critical race condition affecting the recursive directory deletion functionality in Solaris operating systems. This flaw exists within the rm command implementation when using either the -r or -R options for recursive directory removal. The vulnerability stems from improper handling of directory traversal during the deletion process, creating a window where malicious actors can manipulate the filesystem structure to execute unintended operations. The race condition occurs between the time rm begins processing directory contents and when it performs directory changes, allowing for manipulation of the deletion path through strategic file system movements.
The technical implementation of this vulnerability involves the rm command's handling of directory traversal operations during recursive deletion. When rm processes directories recursively, it maintains a current working directory state that can be manipulated by an attacker during the deletion process. The flaw specifically manifests when a low-level directory is moved to a higher level directory while rm is in the process of deleting the parent directory structure. This manipulation causes rm to execute chdir operations to ".." directories that are higher than expected, potentially traversing up to the root file system level. The vulnerability is particularly dangerous because it leverages the natural file system traversal behavior of the rm command to achieve unauthorized access to higher-level directories.
The operational impact of this vulnerability extends beyond simple file deletion to potentially enable complete system compromise. Local users can exploit this race condition to delete files and directories that they would normally not have access to, effectively bypassing normal permission controls and access restrictions. The ability to traverse up to the root file system level means attackers could potentially delete critical system files, compromise system integrity, or create persistent access points. This vulnerability essentially provides a privilege escalation mechanism within the local user context, allowing attackers to perform operations that should be restricted to higher-privilege users or system processes. The flaw is particularly concerning because it affects multiple versions of Solaris 8 through 10, representing a significant attack surface across a wide range of systems.
The vulnerability aligns with CWE-367, which addresses the issue of time-of-check to time-of-use (TOCTOU) race conditions, and demonstrates how improper synchronization between file system checks and operations can lead to security breaches. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques through local exploitation, specifically targeting the system's file system permissions model. The exploitation requires local access and knowledge of the specific timing window, making it a targeted attack vector rather than a widespread exploit. The vulnerability's relationship to CVE-2002-0435 indicates a pattern of similar race condition issues in file system operations, highlighting the need for careful implementation of recursive directory handling. Mitigation strategies should include immediate system patching, implementation of proper file system locking mechanisms, and monitoring for unauthorized file system manipulation during deletion operations.
The root cause of this vulnerability lies in the lack of proper synchronization mechanisms during directory traversal operations in rm's implementation. The command does not adequately validate directory state changes during recursive deletion, creating opportunities for attackers to manipulate the deletion path through file system moves. This flaw demonstrates the importance of proper input validation and state management in system utilities that handle file system operations. System administrators should implement comprehensive monitoring for unusual directory traversal patterns and ensure that all Solaris systems within their environment are updated with the relevant security patches released in February 2007. Additionally, the vulnerability highlights the need for robust testing of file system operations under concurrent access conditions to identify similar race conditions in other system utilities.