CVE-2003-0885 in Xscreensaver
Summary
by MITRE
Xscreensaver 4.14 contains certain debugging code that should have been omitted, which causes Xscreensaver to create temporary files insecurely in the (1) apple2, (2) xanalogtv, and (3) pong screensavers, and allows local users to overwrite arbitrary files via a symlink attack.
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Analysis
by VulDB Data Team • 06/15/2018
The vulnerability identified as CVE-2003-0885 affects Xscreensaver version 4.14 and represents a critical security flaw stemming from the inclusion of debugging code in production software. This issue manifests specifically within three screensaver modules: apple2, xanalogtv, and pong, where the insecure temporary file creation mechanism creates exploitable conditions for local attackers. The presence of debugging code that should have been removed during the software development lifecycle demonstrates poor quality assurance practices and inadequate security review processes. This vulnerability directly violates secure coding principles and represents a classic example of insecure temporary file handling that has been documented in various security frameworks and standards.
The technical exploitation of this vulnerability occurs through symlink attacks that leverage the insecure temporary file creation behavior. When these specific screensavers are executed, they create temporary files in predictable locations without proper security checks, allowing local users to establish symbolic links that point to arbitrary files on the system. This insecure practice creates a race condition scenario where the attacker can manipulate the temporary file creation process to overwrite files of their choice. The vulnerability operates at the file system level and requires local system access, making it a local privilege escalation vector that can be particularly dangerous in multi-user environments where attackers might target sensitive system files or user data. This type of vulnerability is categorized under CWE-377 as "Insecure Temporary File" and falls within the broader category of insecure file handling practices that have been consistently documented in security literature.
The operational impact of this vulnerability extends beyond simple file overwriting capabilities and can lead to significant system compromise when combined with other attack vectors. Local attackers can potentially overwrite critical system files, configuration files, or user data with malicious content, leading to system instability, data corruption, or privilege escalation scenarios. The vulnerability affects Unix-like systems where Xscreensaver is installed and is particularly concerning because screensavers often run with elevated privileges or have access to user data. This creates a persistent threat vector that remains active as long as the vulnerable screensaver module is enabled, making it an attractive target for attackers who might seek to maintain access or cause damage over extended periods. The attack requires minimal privileges and can be executed without network connectivity, making it particularly stealthy and difficult to detect through traditional network monitoring approaches.
Mitigation strategies for this vulnerability require immediate remediation through software updates and patching of the Xscreensaver application to version 4.15 or later where the debugging code has been properly removed. System administrators should disable or remove the vulnerable screensaver modules from systems where they are not essential to prevent exploitation. Additionally, implementing proper file system permissions and monitoring for unauthorized symbolic link creation can provide additional layers of protection. The vulnerability demonstrates the importance of thorough security reviews during software development and the critical need for removing debugging code from production releases. Organizations should also implement regular vulnerability assessments and security audits to identify similar issues in other software components. This vulnerability aligns with ATT&CK technique T1059.007 for execution through screensavers and highlights the need for proper input validation and secure temporary file handling practices as recommended in various security standards including those from the Open Web Application Security Project and NIST guidelines for secure coding practices.