CVE-2006-4781 in TFTP Server Multithreaded
Summary
by MITRE
Heap-based buffer overflow in FutureSoft TFTP Server Multithreaded (MT) 1.1 allows remote attackers to cause a denial of service (crash) or possibly execute arbitrary code by sending a crafted packet to port 69/UDP, which triggers the overflow when constructing an absolute path name. NOTE: Some details are obtained from third party information.
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Analysis
by VulDB Data Team • 07/19/2024
The heap-based buffer overflow vulnerability in FutureSoft TFTP Server Multithreaded version 1.1 represents a critical security flaw that enables remote attackers to compromise system integrity and availability. This vulnerability specifically targets the TFTP protocol implementation running on UDP port 69, which serves as the standard port for Trivial File Transfer Protocol operations. The flaw manifests when the server processes crafted packets during the construction of absolute path names, creating a condition where attacker-controlled data exceeds the allocated heap buffer space. Such vulnerabilities fall under the CWE-121 heap-based buffer overflow category, which is classified as a fundamental memory safety issue that has historically led to numerous security incidents across network services.
The technical exploitation of this vulnerability occurs through carefully crafted UDP packets sent to the target server's port 69, leveraging the server's handling of absolute path construction mechanisms. When the TFTP server receives malicious input during path name processing, it fails to properly validate the length of incoming data against allocated buffer boundaries, resulting in memory corruption that can trigger either a controlled crash or potentially arbitrary code execution. This type of vulnerability is particularly dangerous because it can be exploited remotely without authentication requirements, making it a prime target for automated scanning and exploitation tools. The heap corruption typically occurs in the memory management routines responsible for handling file paths, where the server allocates memory for path construction without adequate bounds checking. The vulnerability demonstrates characteristics consistent with ATT&CK technique T1203, which involves the exploitation of memory corruption vulnerabilities for remote code execution and system compromise.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it can potentially allow attackers to execute arbitrary code with the privileges of the TFTP server process. This presents significant risks for systems where TFTP servers are running with elevated privileges or are part of critical infrastructure components. The vulnerability affects organizations that rely on TFTP for network booting, firmware updates, or other file transfer operations, particularly in environments where network services are not properly monitored or updated. Organizations with outdated TFTP implementations face heightened exposure, as the vulnerability exists in version 1.1 of the FutureSoft server, which represents a legacy implementation that may not receive security updates. The potential for remote code execution makes this vulnerability particularly attractive to threat actors who seek persistent access to network infrastructure, as it provides a foothold for further reconnaissance and lateral movement within the network.
Mitigation strategies for this vulnerability should focus on immediate patching of affected systems, as FutureSoft has likely released updates to address the heap overflow condition. Network segmentation and firewall rules should be implemented to restrict access to UDP port 69 from trusted sources only, reducing the attack surface for this particular vulnerability. Additionally, implementing network monitoring and intrusion detection systems can help identify suspicious traffic patterns associated with TFTP protocol exploitation attempts. The vulnerability highlights the importance of maintaining current security patches and conducting regular vulnerability assessments of network services, particularly legacy implementations that may not receive ongoing security support. Organizations should also consider migrating to more secure and actively maintained TFTP implementations or alternative file transfer protocols such as SFTP or HTTPS that provide better security guarantees and are less susceptible to heap-based buffer overflow exploits.