CVE-2004-0306 in ONS
Summary
by MITRE
Cisco ONS 15327 before 4.1(3), ONS 15454 before 4.6(1), ONS 15454 SD before 4.1(3), and Cisco ONS 15600 before 1.3(0) enable TFTP service on UDP port 69 by default, which allows remote attackers to GET or PUT ONS system files on the current active TCC in the /flash0 or /flash1 directories.
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Analysis
by VulDB Data Team • 03/09/2021
The vulnerability described in CVE-2004-0306 represents a critical security flaw in Cisco's optical network switching equipment, specifically affecting multiple models including the ONS 15327, ONS 15454, ONS 15454 SD, and ONS 15600 series devices. This issue stems from the default configuration of these network appliances that enables the Trivial File Transfer Protocol (TFTP) service on UDP port 69 without proper access controls or authentication mechanisms. The TFTP protocol was designed for simple file transfers in network boot environments and lacks essential security features such as authentication, encryption, or access control, making it inherently vulnerable to exploitation in modern network environments. The vulnerability is particularly concerning as it affects devices that are typically deployed in critical network infrastructure roles where unauthorized access could lead to significant operational disruptions or security breaches.
The technical implementation of this vulnerability allows remote attackers to perform unauthorized file operations on the affected Cisco devices through the TFTP service. Attackers can leverage this service to either retrieve sensitive system files or upload malicious files to the active TCC (Terminal Control Card) components of the network switches. The affected directories /flash0 and /flash1 contain critical system files that are essential for device operation, including configuration files, firmware images, and operational binaries. This capability enables attackers to potentially modify system behavior, install backdoors, or corrupt system files, leading to complete compromise of the affected network equipment. The vulnerability exists due to the default enabling of TFTP without proper network segmentation or access controls, creating an attack surface that is accessible from any network location where the device is exposed to traffic.
From an operational impact perspective, this vulnerability presents a severe risk to network security and stability, particularly in enterprise and service provider environments where these devices are commonly deployed. The ability to remotely access and manipulate system files through TFTP creates multiple attack vectors for adversaries seeking to compromise network infrastructure. Attackers could potentially modify device configurations to redirect traffic, disable security features, or establish persistent access points within the network. The vulnerability also facilitates privilege escalation scenarios where attackers can upload malicious code to gain elevated system privileges and execute arbitrary commands on the affected devices. This type of vulnerability directly violates the principle of least privilege and undermines the security posture of organizations relying on these network switches for critical communications infrastructure.
The exploitation of this vulnerability aligns with several ATT&CK framework techniques including T1078 Valid Accounts, T1566 Phishing, and T1041 Exfiltration. The TFTP service represents a weak point in the security architecture that attackers can leverage to establish persistent access to network infrastructure. Organizations should implement immediate mitigations including disabling the TFTP service on affected devices, applying network segmentation to isolate these devices from untrusted networks, and implementing proper access controls and monitoring for unusual TFTP activity. According to CWE guidelines, this vulnerability corresponds to CWE-255 Credentials Management, as the default configuration fails to properly manage access controls for network services. The recommended remediation strategy involves applying the latest firmware updates from Cisco that address this specific vulnerability, configuring proper network access controls, and implementing network monitoring solutions that can detect and alert on TFTP traffic to or from these devices. Organizations should also conduct comprehensive network audits to identify all affected devices and ensure that TFTP services are disabled unless absolutely required for legitimate network operations.