CVE-2009-3516 in AIX
Summary
by MITRE
gssd in IBM AIX 5.3.x through 5.3.9 and 6.1.0 through 6.1.2 does not properly handle the NFSv4 Kerberos credential cache, which allows local users to bypass intended access restrictions for Kerberized NFSv4 shares via unspecified vectors.
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Analysis
by VulDB Data Team • 02/16/2025
The vulnerability identified as CVE-2009-3516 affects the gssd component in IBM AIX operating systems version 5.3.x through 5.3.9 and 6.1.0 through 6.1.2. This issue specifically targets the handling of NFSv4 Kerberos credential cache mechanisms within the distributed file system implementation. The gssd daemon serves as a critical component in managing security contexts for NFSv4 operations, particularly when Kerberos authentication is employed. The flaw manifests in the improper processing of credential caches that are essential for maintaining secure access to network file systems. This vulnerability represents a significant security weakness in the authentication framework of IBM AIX systems, as it undermines the integrity of access controls that are fundamental to protecting shared resources.
The technical flaw resides in the gssd service's insufficient validation and processing of Kerberos credential cache entries when managing NFSv4 connections. This improper handling creates opportunities for local attackers to exploit weaknesses in the credential management system, potentially allowing unauthorized access to Kerberized NFSv4 shares. The unspecified vectors suggest that the vulnerability could be triggered through various mechanisms within the credential cache processing pipeline, including but not limited to malformed cache entries, improper cache validation, or flawed cache renewal processes. The vulnerability essentially allows privilege escalation or unauthorized access to network resources that should be protected by Kerberos authentication mechanisms.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it compromises the fundamental security model of NFSv4 implementations on IBM AIX systems. Local users who can execute code on affected systems gain the ability to bypass intended access controls, potentially leading to data breaches, privilege escalation, or unauthorized modification of shared resources. This weakness affects the confidentiality, integrity, and availability of networked file systems, particularly in enterprise environments where NFSv4 with Kerberos authentication is commonly deployed. The vulnerability undermines trust in the authentication system and could enable attackers to move laterally within networks where these systems are deployed, as the compromised systems become potential entry points for further attacks.
Organizations should implement immediate mitigations including applying the relevant IBM AIX patches and updates that address the credential cache handling flaw in gssd. System administrators should also consider disabling unnecessary NFSv4 Kerberos authentication where possible, or implementing additional access controls and monitoring for NFSv4 shares. The vulnerability aligns with CWE-284 Access Control Issues, specifically concerning improper access control mechanisms in distributed systems. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques and credential access patterns, as attackers can leverage the flaw to bypass authentication mechanisms and gain elevated privileges within networked file systems. Regular security audits and monitoring of NFSv4 access logs should be implemented to detect potential exploitation attempts, while system hardening measures should focus on restricting local user privileges and implementing least-privilege access controls for NFS services.