CVE-2003-1295 in Xscreensaver
Summary
by MITRE
Unspecified vulnerability in xscreensaver 4.12, and possibly other versions, allows attackers to cause xscreensaver to crash via unspecified vectors "while verifying the user-password."
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Analysis
by VulDB Data Team • 07/04/2017
The vulnerability identified as CVE-2003-1295 represents a critical security flaw within the xscreensaver daemon version 4.12 and potentially other iterations of this popular screen locking utility. This issue manifests during the authentication verification process when users attempt to unlock their screensavers, creating a potential denial of service condition that could be exploited by malicious actors. The xscreensaver application serves as a fundamental component in many unix-like operating systems including linux distributions and freebsd implementations, making this vulnerability particularly concerning from a security perspective as it affects core desktop security mechanisms.
The technical nature of this vulnerability stems from inadequate input validation and error handling within the password verification subsystem of xscreensaver. When users enter their passwords to unlock the screen, the application processes these credentials through an internal verification routine that fails to properly sanitize or validate the input data. This weakness creates opportunities for malformed or specially crafted inputs to trigger unexpected behavior in the application's memory management or control flow, ultimately leading to application crashes and system instability. The vulnerability's classification as unspecified suggests that the exact attack vectors may have been unclear or may have varied depending on system configurations and implementation details, making it particularly challenging to defend against comprehensively.
The operational impact of this vulnerability extends beyond simple system crashes to potentially compromise the security posture of affected systems. When xscreensaver crashes during authentication, users may be forced to restart their desktop environments or reboot entire systems, disrupting productivity and potentially creating windows of vulnerability during restart sequences. This denial of service condition could be particularly dangerous in enterprise environments where screen savers are often configured to lock workstations automatically after periods of inactivity. The vulnerability's potential to affect multiple versions of xscreensaver indicates a fundamental flaw in the codebase rather than a single instance of poor coding, suggesting that organizations running various iterations of this software may be at risk.
Security practitioners should consider this vulnerability in relation to the broader ATT&CK framework, particularly under the initial access and privilege escalation categories where authentication bypasses and service disruptions can create opportunities for further compromise. From a CWE perspective, this vulnerability aligns with several categories including CWE-20 for improper input validation and CWE-119 for memory safety issues, though the exact classification depends on the specific implementation details of how the crash occurs. Organizations should implement immediate mitigations including updating to patched versions of xscreensaver, implementing network-level controls to prevent unauthorized access to systems running vulnerable versions, and monitoring for unusual authentication patterns that might indicate exploitation attempts. The vulnerability also highlights the importance of proper error handling and input validation in security-critical applications, emphasizing that even seemingly benign components like screen savers can become attack vectors when not properly secured against malformed inputs.