CVE-2003-0683 in IRIX
Summary
by MITRE
NFS in SGI 6.5.21m and 6.5.21f does not perform access checks in certain configurations when an /etc/exports entry uses wildcards without any hostnames or groups, which could allow attackers to bypass intended restrictions.
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Analysis
by VulDB Data Team • 04/11/2019
The vulnerability described in CVE-2003-0683 represents a critical access control flaw within the Network File System implementation of SGI's IRIX operating system version 6.5.21m and 6.5.21f. This issue specifically manifests when administrators configure NFS exports using wildcard entries in the /etc/exports file without specifying any hostnames or groups, creating a dangerous configuration that undermines the intended security boundaries of the file sharing mechanism. The flaw stems from insufficient validation of export permissions when wildcards are used in the absence of explicit host or group specifications, allowing unauthorized access to networked file systems that should remain restricted.
The technical root cause of this vulnerability lies in the NFS daemon's failure to properly validate access controls when processing wildcard export entries. When an /etc/exports configuration contains entries with wildcards such as "*" or "+" without accompanying hostname or group specifications, the system does not adequately enforce the intended access restrictions. This creates a scenario where any remote client attempting to access the exported filesystem bypasses the normal access control mechanisms that would typically require explicit host or group membership verification. The flaw operates at the kernel level within the NFS service implementation, making it particularly dangerous as it affects the fundamental security model of network file sharing.
From an operational perspective, this vulnerability presents a significant risk to organizations relying on SGI IRIX systems for file sharing services. Attackers can exploit this weakness to gain unauthorized access to sensitive data that should only be available to specific hosts or user groups, potentially leading to data breaches, privilege escalation, and unauthorized modification of critical system files. The impact extends beyond simple data access, as compromised NFS shares can serve as entry points for further network reconnaissance and lateral movement within the affected infrastructure. This vulnerability directly violates the principle of least privilege and can enable attackers to bypass multiple layers of network security controls that depend on proper NFS export configurations.
The security implications of this vulnerability align with CWE-284, which addresses improper access control issues in software systems, and can be mapped to ATT&CK technique T1078 for valid accounts and T1046 for network service scanning. Organizations should implement immediate mitigations including removal of wildcard entries without explicit host or group specifications from /etc/exports configurations, implementation of more restrictive export rules, and regular audit of NFS export configurations to ensure proper access controls remain in place. System administrators should also consider implementing network segmentation and firewall rules to limit NFS service exposure, while monitoring for unauthorized access attempts to NFS shares. Additionally, the vulnerability demonstrates the importance of proper configuration management and the need for comprehensive security testing of network services, particularly those that handle sensitive data access controls.