CVE-2005-0138 in IRIX
Summary
by MITRE
rpc.mountd in SGI IRIX 6.5.25, 6.5.26, and 6.5.27 does not correctly allow access to anonymous clients that connect from a system whose hostname can not be determined. NOTE: while this issue occurs in a security mechanism, there is no apparent attacker role and probably does not satisfy the CVE definition of a vulnerability.
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Analysis
by VulDB Data Team • 04/11/2019
The vulnerability described in CVE-2005-0138 affects the rpc.mountd service in SGI IRIX operating system versions 6.5.25 through 6.5.27. This issue resides within the Network File System (NFS) implementation where the rpc.mountd daemon fails to properly handle client connections from systems with indeterminate hostnames. The problem manifests when anonymous clients attempt to connect to NFS services but the system cannot resolve their hostname through DNS or other means, creating a potential access control bypass scenario.
The technical flaw stems from improper handling of hostname resolution failures within the rpc.mountd service. When a client connects and the system cannot determine the client's hostname, the service should enforce strict access controls or reject the connection entirely. However, in affected versions, the service appears to grant inappropriate access permissions to these anonymous clients, potentially allowing unauthorized file access through the NFS service. This represents a classic case of insufficient input validation and access control enforcement, where the system fails to properly validate the identity of connecting clients.
The operational impact of this vulnerability is significant within environments relying on NFS services, particularly in research and academic settings where SGI IRIX systems were commonly deployed. While the description notes that no apparent attacker role exists, the vulnerability could potentially be exploited by malicious users within the network who can manipulate hostname resolution or by attackers who can establish connections from systems with unresolved hostnames. The risk increases in environments where NFS services are exposed to untrusted networks or where proper network segmentation is not implemented.
This issue aligns with CWE-284, which addresses improper access control in software systems, and demonstrates how hostname resolution failures can create security gaps in network services. The vulnerability also relates to ATT&CK technique T1071.004, which covers application layer protocol usage, specifically in the context of NFS and RPC services. Organizations should implement proper network segmentation to limit NFS service exposure, ensure proper DNS resolution for all client systems, and regularly update their IRIX systems to patched versions. Additionally, monitoring for unusual NFS access patterns and implementing strict firewall rules for NFS ports 111 and 2049 can help mitigate potential exploitation attempts. The vulnerability underscores the importance of robust input validation and access control mechanisms in network services, particularly those that handle anonymous connections and rely on hostname resolution for security decisions.