CVE-2008-5184 in CUPS
Summary
by MITRE
The web interface (cgi-bin/admin.c) in CUPS before 1.3.8 uses the guest username when a user is not logged on to the web server, which makes it easier for remote attackers to bypass intended policy and conduct CSRF attacks via the (1) add and (2) cancel RSS subscription functions.
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Analysis
by VulDB Data Team • 08/03/2021
The vulnerability described in CVE-2008-5184 affects the Common Unix Printing System (CUPS) version 1.3.7 and earlier, specifically targeting the web-based administration interface located at cgi-bin/admin.c. This flaw represents a significant security weakness in the authentication and authorization mechanisms of the printing system's web interface. The vulnerability stems from the improper handling of user authentication states within the web server environment, creating a persistent security gap that could be exploited by remote attackers to bypass intended access controls.
The technical implementation flaw occurs when users attempt to access the CUPS web administration interface without proper authentication. Instead of enforcing strict authentication requirements or redirecting unauthorized users to a login page, the system defaults to using a guest username for all unauthenticated requests. This design decision creates a fundamental security weakness that allows attackers to manipulate the web interface without proper authorization. The vulnerability specifically impacts two critical functions related to RSS subscription management, namely the add and cancel RSS subscription operations, which are commonly used for system monitoring and notification services.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it enables sophisticated attack vectors including cross-site request forgery (CSRF) exploitation. Attackers can leverage this flaw to perform unauthorized actions against the CUPS system by crafting malicious requests that appear to originate from authenticated users. The guest username default creates a false sense of security for legitimate users who expect their actions to be properly authenticated and authorized. This vulnerability undermines the integrity of the system's access control mechanisms and could potentially allow attackers to modify printer configurations, add malicious subscriptions, or cancel legitimate ones without proper authorization.
The security implications of this vulnerability align with CWE-285, which addresses improper authorization issues in software systems, and can be mapped to ATT&CK technique T1078.1.1 for valid accounts and T1566.001 for credential access through web application attacks. The flaw demonstrates poor input validation and authentication handling practices that are commonly exploited in web-based attacks. Organizations using affected CUPS versions face increased risk of unauthorized printer management activities, potential data exposure through compromised subscription functions, and possible escalation to more severe system compromises.
Mitigation strategies should prioritize immediate patching of the CUPS software to version 1.3.8 or later, where the authentication handling has been properly addressed. System administrators should also implement additional network-level controls such as firewall rules to restrict access to the cgi-bin/admin.c endpoint, particularly from untrusted networks. Network segmentation and access control lists can help limit exposure of the vulnerable web interface to only authorized administrative users. Regular security audits of web applications and authentication mechanisms should be conducted to identify similar vulnerabilities in other system components. The vulnerability serves as a reminder of the critical importance of proper authentication handling in web applications and demonstrates how seemingly minor implementation flaws can create significant security risks.