CVE-2001-0185 in R9100 Router
Summary
by MITRE
Netopia R9100 router version 4.6 allows authenticated users to cause a denial of service by using the router s telnet program to connect to the router s IP address, which causes a crash.
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Analysis
by VulDB Data Team • 04/07/2019
The vulnerability identified as CVE-2001-0185 affects the Netopia R9100 router running firmware version 4.6 and represents a denial of service weakness that can be exploited by authenticated users. This issue stems from improper input validation within the router's telnet implementation, specifically when processing connection requests to the router's own IP address. The flaw exists in the router's network services handling mechanism where the telnet daemon fails to properly validate or sanitize connection parameters before processing them, leading to a potential crash condition that renders the device unavailable to legitimate users.
This vulnerability operates through a specific attack vector where an authenticated user can establish a telnet session to the router's own IP address, triggering an unhandled exception in the telnet service implementation. The technical flaw manifests as a buffer overflow or memory corruption issue within the telnet daemon code, causing the process to terminate unexpectedly and resulting in a complete service disruption. The router's telnet service does not properly validate the connection request parameters, particularly when the target address matches the device's own IP address, creating a recursive or self-referential condition that leads to system instability.
The operational impact of this vulnerability extends beyond simple service disruption as it can be exploited by malicious insiders or compromised accounts to render network infrastructure unavailable. Network administrators may experience significant downtime as the router becomes unresponsive, potentially affecting internet connectivity for all devices relying on that specific router. The vulnerability is particularly concerning because it requires only authenticated access, meaning that any user with valid credentials can exploit this weakness. This type of vulnerability aligns with CWE-122 which addresses buffer overflow conditions, and represents a classic example of improper input validation that can lead to system instability.
From a cybersecurity perspective, this vulnerability demonstrates the importance of proper service validation and input sanitization in network device firmware. The attack pattern follows principles consistent with the attack technique T1499.004 from the MITRE ATT&CK framework, which covers network denial of service attacks. Organizations should implement proper access controls and network segmentation to limit the potential impact of such vulnerabilities, while also ensuring that network devices receive regular firmware updates. The vulnerability also highlights the need for robust error handling in embedded systems and network services, as the lack of proper exception handling in the telnet daemon creates a predictable crash condition that can be reliably exploited by authenticated users. Network security teams should consider implementing monitoring for unusual telnet connection patterns and ensure that routers are configured with minimal necessary services to reduce the attack surface.