CVE-2004-2637 in Zsr1104we Wireless Router Runtime Code
Summary
by MITRE
The NAT implementation in Zonet ZSR1104WE Wireless Router Runtime Code Version 2.41 converts IP addresses of inbound connections to the IP address of the router, which allows remote attackers to bypass intended security restrictions.
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Analysis
by VulDB Data Team • 07/19/2017
The vulnerability described in CVE-2004-2637 represents a critical flaw in the network address translation implementation of the Zonet ZSR1104WE Wireless Router firmware version 2.41. This issue stems from improper handling of inbound connection traffic where the router's NAT functionality fails to maintain proper source IP address tracking during connection translation processes. The flaw creates a security boundary violation that undermines the fundamental purpose of network address translation as a security mechanism.
The technical root cause of this vulnerability lies in the router's failure to properly maintain connection state information during NAT processing. When inbound connections arrive at the router, the system incorrectly maps these connections to the router's own IP address rather than preserving the original source address information. This misconfiguration allows attackers to exploit the NAT translation process to bypass access controls that should restrict traffic based on source IP addresses. The vulnerability specifically affects the runtime code execution environment of the router's firmware, indicating a flaw in the core networking stack implementation.
The operational impact of this vulnerability is severe as it enables remote attackers to circumvent network security policies that rely on proper NAT behavior for access control. An attacker could potentially gain unauthorized access to internal network resources by exploiting the flawed IP address conversion mechanism. This vulnerability essentially undermines the router's ability to provide network isolation and access control, allowing external parties to establish connections that should be restricted by the router's security policies. The flaw affects the router's ability to maintain proper network boundaries and can lead to unauthorized data access or service exploitation.
From a cybersecurity perspective, this vulnerability aligns with CWE-693, which covers protection mechanism failures in network security contexts. The issue demonstrates a failure in proper connection tracking and state management that violates fundamental network security principles. According to ATT&CK framework category T1071.001, this vulnerability could enable network protocol manipulation techniques that allow attackers to bypass network defenses. The flaw represents a classic example of how improper state management in network devices can create security loopholes that undermine the entire network security architecture.
Mitigation strategies for this vulnerability should prioritize immediate firmware updates from Zonet to address the NAT implementation flaw. Network administrators should implement additional access controls such as firewall rules that explicitly restrict inbound connections to the router itself and monitor for unusual traffic patterns. The router configuration should be reviewed to ensure proper port filtering and access control lists are in place to compensate for the NAT flaw. Additionally, network segmentation techniques should be employed to limit the potential impact of successful exploitation attempts, and regular security audits should verify that the router's NAT functionality operates correctly according to security policy requirements.