CVE-2001-0617 in AT-AR220e
Summary
by MITRE
Allied Telesyn AT-AR220e cable/DSL router firmware 1.08a RC14 with the portmapper and the Virtual Server enabled can allow a remote attacker to gain access to mapped services even though the single portmappings may be disabled.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 06/01/2018
The Allied Telesyn AT-AR220e router represents a significant security vulnerability classified as CVE-2001-0617, where the firmware version 1.08a RC14 contains a critical flaw in its port mapping implementation. This vulnerability stems from a design oversight in how the router handles port mapping configurations, specifically when both the portmapper and virtual server functionalities are enabled simultaneously. The flaw allows remote attackers to bypass intended security restrictions and gain unauthorized access to services that should be protected by disabled port mappings.
The technical nature of this vulnerability resides in the router's handling of network address translation and port forwarding mechanisms. When the portmapper service is active alongside virtual server configurations, the device fails to properly enforce access controls for individual port mappings. This creates a scenario where even though specific port mappings have been disabled through the user interface or configuration settings, the underlying network protocols continue to permit access to the mapped services. The vulnerability operates at the network layer and exploits the router's insufficient validation of port mapping states, creating a persistent backdoor for unauthorized access.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it fundamentally undermines the security model implemented by network administrators. Attackers can exploit this weakness to gain access to internal services that are typically protected behind the router's firewall, including but not limited to web servers, ftp services, and other network applications. This represents a critical failure in the router's security architecture where the principle of least privilege is violated, allowing attackers to bypass configured security policies. The vulnerability affects organizations that rely on port mapping for legitimate network access while expecting proper isolation of internal services.
The flaw demonstrates characteristics consistent with CWE-284, which addresses improper access control in software systems, and aligns with ATT&CK technique T1071.001 for application layer protocol usage. This vulnerability essentially creates a false sense of security for administrators who believe that disabling port mappings provides adequate protection for their network services. The security implications are particularly severe for small to medium businesses that may not have sophisticated network monitoring in place to detect unauthorized access attempts. Organizations using this router configuration are vulnerable to reconnaissance activities and potential exploitation of other services running on the mapped ports.
Mitigation strategies for this vulnerability require immediate attention from network administrators, including disabling both the portmapper and virtual server functionalities if they are not absolutely necessary for operations. The most effective remediation involves updating to firmware versions that properly address the port mapping validation issue, though many older devices may not receive security updates. Network segmentation and additional firewall rules can provide temporary protection, while monitoring for unusual traffic patterns on mapped ports should be implemented. Organizations should also consider implementing network access control lists and regular security audits to identify potential exploitation attempts. The vulnerability highlights the importance of proper security testing during network device deployment and the need for comprehensive understanding of how different router services interact with each other.