CVE-2004-0476 in OfficeConnect Remote 812 ADSL Router
Summary
by MITRE
Buffer overflow in 3Com OfficeConnect Remote 812 ADSL Router 1.1.9.4 allows remote attackers to cause a denial of service (reboot or packet loss) via a long string containing Telnet escape characters to the Telnet port.
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Analysis
by VulDB Data Team • 06/28/2019
The vulnerability identified as CVE-2004-0476 represents a critical buffer overflow flaw within the 3Com OfficeConnect Remote 812 ADSL Router firmware version 1.1.9.4. This security weakness specifically affects the router's Telnet service implementation, creating an avenue for remote attackers to exploit the device's network communication protocols. The vulnerability stems from insufficient input validation mechanisms within the Telnet server component, which fails to properly handle excessively long strings containing Telnet escape sequences. When the router processes malformed input data exceeding predetermined buffer limits, the overflow condition triggers unpredictable behavior within the device's memory management systems.
The technical exploitation of this vulnerability occurs through the deliberate injection of lengthy strings containing Telnet escape characters into the Telnet port service. These escape sequences are designed to manipulate terminal behavior and communication protocols, but when processed by the vulnerable router, they exceed the allocated buffer space. The buffer overflow condition results in memory corruption that affects the router's execution flow, causing the device to either reboot unexpectedly or experience significant packet loss. This behavior directly impacts the availability of network services, as the router becomes temporarily inaccessible to legitimate users and network traffic experiences disruption. The flaw demonstrates poor input sanitization practices and inadequate bounds checking mechanisms that are fundamental requirements for secure network device implementations.
From an operational perspective, this vulnerability poses substantial risk to network infrastructure integrity and availability. The remote nature of the attack means that adversaries can exploit the flaw from external network positions without requiring physical access to the device or specialized network credentials. The resulting denial of service conditions can persist until manual intervention occurs, potentially causing extended network outages for organizations relying on the affected router for internet connectivity. Network administrators face the challenge of identifying vulnerable devices within their infrastructure, as the exploitation may not be immediately apparent and could occur during periods of low network activity. The impact extends beyond simple service interruption to potentially disrupt critical business operations that depend on uninterrupted network connectivity.
The vulnerability aligns with CWE-121, which addresses stack-based buffer overflow conditions, and demonstrates characteristics consistent with the attack patterns documented in MITRE ATT&CK framework under the T1210 technique for exploitation of remote services. Security professionals should implement immediate mitigations including firmware updates to address the underlying buffer overflow condition, network segmentation to limit exposure of vulnerable devices, and monitoring of Telnet port traffic for suspicious activity. Additionally, organizations should consider disabling unnecessary services such as Telnet when SSH alternatives are available, as the Telnet protocol's lack of encryption combined with this vulnerability creates a particularly dangerous combination. Regular vulnerability assessments and network scanning should identify all instances of this router model within the network infrastructure to ensure comprehensive remediation coverage. The incident underscores the importance of secure coding practices and proper input validation in network device firmware development, particularly for services that handle external network communications and user input processing.