CVE-2004-0390 in OpenServer
Summary
by MITRE
SCO OpenServer 5.0.5 through 5.0.7 only supports Xauthority style access control when users log in using scologin, which allows remote attackers to gain unauthorized access to an X session via other X login methods.
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Analysis
by VulDB Data Team • 06/30/2025
The vulnerability described in CVE-2004-0390 represents a critical access control flaw within SCO OpenServer operating systems version 5.0.5 through 5.0.7. This issue stems from the implementation of Xauthority style access control mechanisms that are specifically tied to the scologin authentication method. The core problem lies in the inconsistent application of security controls across different login pathways, creating a significant security gap that attackers can exploit to bypass legitimate authentication processes.
The technical flaw manifests when users authenticate through methods other than scologin, such as traditional X login procedures or alternative authentication mechanisms. In these scenarios, the system fails to properly enforce Xauthority style access control, which is designed to restrict X session access based on authentication credentials and user permissions. This creates an insecure state where remote attackers can establish unauthorized X sessions without proper authentication, effectively bypassing the intended security boundaries that should protect graphical user interfaces and their associated resources.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it fundamentally undermines the security model of the X Window System implementation within SCO OpenServer. Attackers exploiting this weakness can gain access to graphical sessions, potentially leading to complete system compromise through graphical interface exploitation, credential theft, or unauthorized system manipulation. The vulnerability particularly affects environments where multiple login methods are supported, as the inconsistency in access control enforcement creates multiple attack vectors that attackers can leverage.
Organizations running affected SCO OpenServer versions face significant risk exposure given that the flaw exists at the core authentication layer of the graphical interface system. The vulnerability aligns with CWE-284 access control weaknesses and maps to ATT&CK technique T1078 for valid accounts, as it enables unauthorized access through legitimate login mechanisms. Mitigation strategies should focus on implementing consistent access control policies across all login methods, updating to patched versions of the operating system, and potentially disabling non-essential X login methods until proper authentication controls can be enforced. Additionally, network segmentation and monitoring of X session activity can help detect and prevent exploitation attempts while more permanent solutions are implemented.