CVE-2007-5958 in Xserver
Summary
by MITRE
X.Org Xserver before 1.4.1 allows local users to determine the existence of arbitrary files via a filename argument in the -sp option to the X program, which produces different error messages depending on whether the filename exists.
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Analysis
by VulDB Data Team • 10/17/2024
The vulnerability identified as CVE-2007-5958 affects the X.Org Xserver version 1.4.1 and earlier, representing a significant information disclosure flaw that impacts local users within the X Window System environment. This issue stems from the improper handling of filename arguments within the X program's -sp option, which is designed for specifying the server's socket path. The vulnerability operates by leveraging the server's error message generation mechanism to infer file existence through subtle variations in error responses, creating a covert channel for information gathering.
The technical implementation of this vulnerability exploits the Xserver's response behavior when processing invalid file paths through the -sp command line argument. When a user provides a filename argument to the -sp option, the Xserver generates distinct error messages depending on whether the specified file exists or not. This differential response creates a timing-based information leak where an attacker can systematically test file paths and observe the server's error message variations to determine file existence. The flaw resides in the server's insufficient sanitization and error handling of user-provided filename arguments, violating fundamental security principles of least privilege and information hiding.
Operationally, this vulnerability enables local attackers to perform reconnaissance activities by mapping out the filesystem structure without direct access to the underlying operating system. The impact extends beyond simple file enumeration to potentially reveal sensitive system information, directory structures, and file permissions that could aid in subsequent exploitation attempts. Attackers can leverage this information to identify system configuration files, user-specific data, or other targets of interest. The vulnerability particularly affects environments where multiple users share the same X server instance, as local users can exploit this weakness to gather intelligence about other user files and system resources, creating a potential escalation path for privilege escalation or targeted attacks.
Mitigation strategies for CVE-2007-5958 should focus on upgrading to X.Org Xserver version 1.4.1 or later, which includes proper error handling and sanitization of filename arguments. System administrators should implement proper access controls to limit local user privileges and consider disabling unnecessary X server options that could expose similar information disclosure vulnerabilities. The vulnerability aligns with CWE-200, Information Exposure, and represents a classic example of how improper error handling can create security weaknesses. From an ATT&CK framework perspective, this vulnerability maps to T1083 (File and Directory Discovery) and T1068 (Exploitation for Privilege Escalation), as it enables reconnaissance activities that can lead to more sophisticated attacks. Organizations should also implement monitoring for unusual X server error message patterns and consider implementing additional logging mechanisms to detect potential exploitation attempts, as the vulnerability demonstrates how seemingly benign error handling can create significant security implications in multi-user environments.