CVE-2004-1636 in WvTFTPServer
Summary
by MITRE
Heap-based buffer overflow in the WvTFTPServer::new_connection function in wvtftpserver.cc for WvTftp 0.9 allows remote attackers to execute arbitrary code via a long option string in a TFTP packet.
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Analysis
by VulDB Data Team • 01/01/2025
The vulnerability identified as CVE-2004-1636 represents a critical heap-based buffer overflow within the WvTftp 0.9 software implementation of the Trivial File Transfer Protocol. This flaw exists specifically within the WvTFTPServer::new_connection function located in the wvtftpserver.cc source file, creating a significant security risk for systems that rely on this TFTP server implementation. The vulnerability stems from inadequate input validation and bounds checking when processing TFTP packets, particularly those containing option strings that exceed predetermined buffer limits. The flaw enables remote attackers to manipulate memory layout and potentially execute arbitrary code on affected systems, making it a severe threat vector for network-based exploitation.
The technical implementation of this vulnerability involves the improper handling of option strings within TFTP packets, where the WvTftp server fails to validate the length of incoming option parameters before copying them into fixed-size heap buffers. This classic buffer overflow condition occurs when an attacker crafts a malicious TFTP packet containing an excessively long option string that overflows the allocated buffer space, potentially overwriting adjacent memory regions including return addresses and control data. The heap-based nature of the overflow means that the memory corruption affects dynamically allocated memory regions rather than stack-based buffers, complicating exploitation techniques and potentially making the vulnerability more resistant to standard exploit mitigations. This issue directly maps to CWE-121, heap-based buffer overflow, and represents a fundamental flaw in memory management practices within the TFTP server implementation.
The operational impact of CVE-2004-1636 extends beyond simple code execution capabilities, as it provides attackers with potential persistence mechanisms and privilege escalation opportunities within affected network environments. Systems running vulnerable WvTftp servers become susceptible to remote code execution attacks that could allow attackers to establish backdoors, escalate privileges, or compromise entire network segments that rely on TFTP for file transfers. The vulnerability affects network infrastructure components such as routers, switches, and network management systems that commonly utilize TFTP for firmware updates and configuration file transfers. Attackers could leverage this vulnerability to gain unauthorized access to network devices, potentially disrupting services or creating persistent access points within the network infrastructure. The attack surface is particularly concerning in enterprise environments where TFTP servers are commonly deployed for automated network device management and firmware distribution processes.
Mitigation strategies for this vulnerability require immediate patching of affected WvTftp installations to the latest available versions that contain proper input validation and buffer size checking mechanisms. System administrators should implement network segmentation and access controls to limit exposure of TFTP services to trusted network segments, while also deploying intrusion detection systems to monitor for suspicious TFTP traffic patterns. The implementation of network-based firewall rules to restrict TFTP traffic to authorized hosts and ports provides an additional defensive layer against exploitation attempts. Organizations should also conduct thorough inventory assessments to identify all systems running vulnerable WvTftp versions and prioritize remediation efforts based on risk exposure and criticality of affected services. This vulnerability demonstrates the importance of proper input validation and memory safety practices in network services, aligning with ATT&CK technique T1059.007 for command and script injection and highlighting the need for robust software security practices throughout the development lifecycle. Regular security assessments and vulnerability scanning should be implemented to identify similar memory corruption vulnerabilities in other network services and prevent similar exploitation scenarios from occurring in the future.