CVE-2002-1968 in DOXport 1100
Summary
by MITRE
Com21 DOXport 1100 series cable modem running firmware 2.1.1.106, and possibly other versions before 2.1.1.108.003, downloads a DOCSIS configuration file from a TFTP server running on the internal network, which allows local users to modify configuration of the modem via a malicious TFTP server.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 04/19/2019
The CVE-2002-1968 vulnerability affects Com21 DOXport 1100 series cable modems operating with firmware versions prior to 2.1.1.108.003, representing a critical security flaw in network infrastructure devices that enables local privilege escalation through unauthorized configuration modification. This vulnerability stems from the modem's insecure handling of DOCSIS configuration files obtained via TFTP protocol from internal network servers, creating a significant attack surface for malicious actors within the local network perimeter. The issue resides in the modem's trust model, where it automatically accepts and applies configuration data from any TFTP server without proper authentication or validation mechanisms, effectively allowing any local user with network access to manipulate the device's operational parameters.
The technical implementation of this vulnerability involves the modem's reliance on TFTP for configuration file retrieval, which operates without encryption or authentication controls. When the modem connects to a TFTP server on the internal network, it downloads and applies configuration settings without verifying the server's authenticity or the integrity of the downloaded file. This design flaw allows attackers to host a malicious TFTP server that responds to the modem's requests with altered configuration data, potentially enabling them to modify network settings, disable security features, redirect traffic, or establish unauthorized access points within the network infrastructure. The vulnerability specifically impacts the modem's configuration management process, creating a path for privilege escalation that bypasses normal access controls and authentication mechanisms.
The operational impact of CVE-2002-1968 extends beyond simple configuration modification, as it fundamentally compromises the integrity and security of the entire network infrastructure that relies on these modems for connectivity. Local users with access to the internal network can exploit this vulnerability to gain unauthorized control over the modem's operational parameters, potentially leading to network disruption, data interception, or unauthorized access to downstream network resources. The vulnerability's exploitation can result in complete compromise of the modem's functionality, enabling attackers to redirect traffic through malicious servers, disable security features, or establish persistent access points within the network. This represents a significant risk to network security posture, as it allows attackers to manipulate core network infrastructure devices without requiring external network access or sophisticated attack vectors.
The vulnerability aligns with CWE-200, which addresses improper output sanitization, and CWE-502, concerning deserialization of untrusted data, as the modem blindly accepts and processes configuration data from unauthenticated sources. From an ATT&CK framework perspective, this vulnerability maps to T1059.007 for command and scripting interpreter and T1566 for phishing to gain initial access, as attackers can leverage the compromised modem to establish persistent network access. Mitigation strategies should include immediate firmware updates to version 2.1.1.108.003 or later, network segmentation to isolate modem communication, implementation of network access controls to restrict TFTP server access, and monitoring for unauthorized TFTP traffic. Additionally, organizations should consider disabling TFTP functionality when not required, implementing network intrusion detection systems to monitor for malicious TFTP activities, and establishing proper network access controls to prevent local users from accessing potentially malicious TFTP servers. The vulnerability demonstrates the critical importance of secure configuration management in network infrastructure devices and highlights the necessity of proper authentication and validation mechanisms in all network communication protocols.