CVE-2003-0796 in IRIX
Summary
by MITRE
Unknown vulnerability in rpc.mountd SGI IRIX 6.5.18 through 6.5.22 allows remote attackers to mount from unprivileged ports even with the -n option disabled.
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Analysis
by VulDB Data Team • 04/11/2019
The vulnerability identified as CVE-2003-0796 affects the rpc.mountd service on SGI IRIX operating systems version 6.5.18 through 6.5.22. This represents a significant security flaw in the Network File System (NFS) implementation that undermines fundamental network security controls. The rpc.mountd service is responsible for managing NFS mount requests and typically operates with strict port binding requirements to prevent unauthorized access. The flaw specifically relates to how the service handles port validation when the -n option is disabled, creating an avenue for remote attackers to exploit the system's network security posture.
The technical nature of this vulnerability stems from improper validation of source port information during NFS mount operations. When rpc.mountd operates without the -n option, it should normally restrict mount requests to privileged ports or enforce strict source port validation. However, this vulnerability allows attackers to craft mount requests from unprivileged ports, effectively bypassing the intended security controls. This behavior violates the principle of least privilege and demonstrates a failure in the service's authentication and authorization mechanisms. The flaw essentially creates a backdoor mechanism that permits unauthorized network access through the NFS subsystem, potentially enabling attackers to gain elevated system access or perform unauthorized file operations.
The operational impact of this vulnerability extends beyond simple network access violations and represents a serious threat to system integrity and data confidentiality. Remote attackers who successfully exploit this vulnerability can mount NFS shares from unprivileged ports, potentially gaining access to sensitive system files, directories, and data stored on the affected system. This could lead to complete system compromise, data exfiltration, or the ability to establish persistent access through the NFS service. The vulnerability is particularly concerning because it affects a core network service that is often enabled by default, making it an attractive target for automated exploitation attempts. The security implications are amplified by the fact that the -n option, which is designed to enhance security by preventing unprivileged port usage, becomes ineffective due to this flaw.
Mitigation strategies for CVE-2003-0796 should focus on immediate patching of the affected IRIX systems and implementation of network-level controls to prevent exploitation. Organizations should apply the vendor-provided security patches as soon as they become available, as this vulnerability has been known since 2003 and represents a well-documented security flaw. Network administrators should also implement firewall rules to restrict access to the rpc.mountd service and related NFS ports, particularly blocking incoming connections from unprivileged ports. The mitigation approach aligns with security framework principles that emphasize defense in depth, as outlined in the NIST Cybersecurity Framework and ISO 27001 standards. Additionally, monitoring for unusual mount requests and implementing intrusion detection systems can help identify exploitation attempts. This vulnerability is classified under CWE-284 as an "Improper Access Control" and maps to ATT&CK technique T1046 for Network Service Scanning and T1059 for Command and Scripting Interpreter, demonstrating how this flaw can enable further exploitation within a network environment.