CVE-2013-6410 in nbd
Summary
by MITRE
nbd-server in Network Block Device (nbd) before 3.5 does not properly check IP addresses, which might allow remote attackers to bypass intended access restrictions via an IP address that has a partial match in the authfile configuration file.
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Analysis
by VulDB Data Team • 01/11/2022
The vulnerability identified as CVE-2013-6410 affects the nbd-server component within the Network Block Device implementation prior to version 3.5. This flaw resides in the authentication mechanism where the server fails to properly validate IP addresses during the access control process. The issue manifests when the nbd-server processes authentication requests and encounters IP addresses that contain partial matches within the configured authfile, creating a potential security bypass scenario that could allow unauthorized access to network block devices.
The technical implementation of this vulnerability stems from inadequate input validation within the nbd-server's IP address handling logic. When processing authentication requests, the server performs pattern matching against configured IP addresses in the authfile without implementing strict validation measures. This allows attackers to craft IP addresses that partially match legitimate entries in the configuration file, effectively circumventing the intended access controls. The flaw operates at the protocol level where IP address validation is insufficiently enforced, creating a window for malicious actors to exploit the authentication mechanism.
Operational impact of this vulnerability extends beyond simple unauthorized access, as it represents a critical weakness in the security architecture of network block device implementations. Remote attackers can leverage this flaw to gain access to protected storage resources without proper authentication credentials, potentially leading to data breaches, unauthorized data modification, or system compromise. The vulnerability affects organizations relying on nbd-server for storage virtualization and remote disk access, particularly those with less stringent network segmentation practices. The partial matching behavior creates a false sense of security where administrators might believe their access controls are robust, while the underlying implementation remains vulnerable to exploitation.
Mitigation strategies for CVE-2013-6410 should prioritize immediate software updates to nbd-server versions 3.5 and later, which contain the necessary fixes for proper IP address validation. Organizations should also implement network segmentation and firewall rules to restrict access to nbd-server ports, ensuring that only trusted IP addresses can communicate with the service. Additional defensive measures include configuring strict IP address matching rules in authfiles, implementing monitoring for unusual authentication patterns, and conducting regular security audits of network block device configurations. The vulnerability aligns with CWE-284, which addresses improper access control issues, and represents a specific instance where weak input validation leads to privilege escalation through authentication bypass mechanisms.
From an adversarial perspective, this vulnerability maps to several ATT&CK techniques including T1078 for valid accounts and T1046 for network service scanning, as attackers would need to identify the service and potentially exploit the authentication bypass to gain access to storage resources. The remediation approach should include comprehensive testing of updated configurations to ensure that legitimate users maintain access while unauthorized parties are properly denied. Organizations should also consider implementing additional layers of security such as encrypted connections and multi-factor authentication for critical storage systems to provide defense in depth against similar vulnerabilities.