CVE-2004-0921 in Mac OS X
Summary
by MITRE
AFP Server on Mac OS X 10.3.x to 10.3.5, when a guest has mounted an AFP volume, allows the guest to "terminate authenticated user mounts" via modified SessionDestroy packets.
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Analysis
by VulDB Data Team • 05/30/2019
The vulnerability described in CVE-2004-0921 represents a significant security flaw in the Apple Filing Protocol server implementation within Mac OS X versions 10.3 through 10.3.5. This issue specifically targets the AFP server's handling of session management and authentication states, creating a scenario where unauthenticated or guest users can manipulate the system to disrupt legitimate user sessions. The vulnerability exploits a fundamental weakness in the server's packet processing mechanism, particularly when dealing with SessionDestroy packets that are normally used to properly terminate authenticated sessions.
The technical flaw manifests through improper validation of SessionDestroy packets received from guest users who have already mounted an AFP volume. When a guest user establishes an AFP connection to the server, they maintain a session state that should normally be protected from manipulation by unauthorized parties. However, the AFP server fails to adequately authenticate or validate the source of SessionDestroy packets, allowing a malicious guest user to craft and send modified packets that appear to originate from authenticated users. This misconfiguration enables the guest to issue commands that instruct the server to terminate legitimate user mounts, effectively creating a denial of service condition that impacts other authenticated users who rely on the AFP service for file access.
The operational impact of this vulnerability extends beyond simple service disruption, as it fundamentally undermines the security model of the AFP server by allowing unauthorized session manipulation. When a guest user can terminate authenticated user mounts, they effectively gain the ability to disrupt file access for legitimate users who may be working with shared resources or accessing critical data through the AFP service. This vulnerability particularly affects environments where multiple users access shared file systems through AFP, as it creates opportunities for both accidental and intentional disruption of file services. The attack vector is relatively simple to execute since it only requires a guest user with access to mount an AFP volume and then send modified packets, making it a particularly concerning weakness in the system's security architecture.
This vulnerability aligns with CWE-284, which addresses improper access control mechanisms, and represents a clear failure in session management security. The issue also maps to ATT&CK technique T1499.004, which covers "Toggle Service State" through denial of service attacks that manipulate service states. Organizations using Mac OS X 10.3.x through 10.3.5 should implement immediate mitigations including updating to patched versions of the operating system, implementing network segmentation to limit guest access to AFP services, and configuring proper access controls that restrict session management capabilities to authenticated users only. Additionally, monitoring network traffic for suspicious SessionDestroy packet patterns can help detect potential exploitation attempts. The vulnerability demonstrates the importance of proper input validation and authentication in network services, particularly those handling session state information that can affect other users within the same service environment.