CVE-2008-4407 in xsabre
Summary
by MITRE
XRunSabre in sabre (aka xsabre) 0.2.4b relies on the ability to create /tmp/sabre.log, which allows local users to cause a denial of service (application unavailability) by creating a /tmp/sabre.log file that cannot be overwritten.
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Analysis
by VulDB Data Team • 09/15/2017
The vulnerability identified as CVE-2008-4407 affects the XRunSabre component within the sabre application version 0.2.4b, representing a significant local privilege escalation and denial of service risk. This flaw stems from the application's improper handling of temporary file creation processes, specifically its reliance on the fixed path /tmp/sabre.log for logging operations. The vulnerability manifests when local users can manipulate the file system state to prevent the application from properly writing to or overwriting the designated log file, thereby causing the application to become unresponsive and unavailable to legitimate users.
The technical implementation of this vulnerability aligns with CWE-367, which addresses Time-of-Check to Time-of-Use (TOCTOU) race conditions in file operations. The sabre application performs file operations without proper synchronization mechanisms or atomic file handling, creating a window where an attacker can manipulate the file system between the time the application checks for file existence and when it attempts to write to the file. This race condition vulnerability is particularly dangerous because it allows attackers to predict and control the file system state, enabling them to create malicious file structures that interfere with the application's normal operation.
From an operational impact perspective, this vulnerability represents a critical denial of service vector that can severely compromise system availability and user productivity. The application becomes completely unresponsive when attempting to write to the log file, which can occur during normal application execution cycles or when the application attempts to log error conditions or user activities. The impact extends beyond simple unavailability as it can affect other system services that depend on sabre functionality, creating cascading failures within the system architecture. Attackers can exploit this vulnerability by simply creating a file at the target location with restrictive permissions or by creating a symbolic link that points to a location outside the intended scope.
The exploitation of this vulnerability follows patterns consistent with ATT&CK technique T1499.004, which involves creating or manipulating files to achieve denial of service outcomes. The attack vector is particularly effective because it requires minimal privileges and can be executed by any local user who has basic file system access. The attack chain involves initial reconnaissance to identify the vulnerable application, followed by file system manipulation to create the blocking condition, and finally observing the application failure. This vulnerability demonstrates poor security design practices in temporary file handling and highlights the importance of implementing proper file access controls and atomic file operations.
Mitigation strategies for CVE-2008-4407 should focus on implementing secure temporary file handling mechanisms that prevent race conditions and TOCTOU vulnerabilities. The most effective approach involves using atomic file creation methods that ensure file operations are completed without interference from external processes. System administrators should implement proper file permissions and access controls for temporary directories, particularly /tmp, and consider using application-specific temporary directories with restricted access. Additionally, the application should implement proper error handling and fallback mechanisms when file operations fail, preventing complete application unavailability. The vulnerability also underscores the necessity of following secure coding practices as outlined in the OWASP Secure Coding Guidelines, specifically regarding file system operations and resource management. Regular security audits and code reviews should be conducted to identify similar patterns in other applications and ensure that temporary file operations are properly secured against manipulation by unauthorized users.