CVE-2009-3115 in TFTP Server
Summary
by MITRE
SolarWinds TFTP Server 9.2.0.111 and earlier allows remote attackers to cause a denial of service (service stop) via a crafted Option Acknowledgement (OACK) request. NOTE: some of these details are obtained from third party information.
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Analysis
by VulDB Data Team • 02/27/2025
The vulnerability identified as CVE-2009-3115 affects SolarWinds TFTP Server version 9.2.0.111 and earlier, representing a critical denial of service weakness that can be exploited by remote attackers to disrupt network services. This flaw specifically targets the TFTP protocol implementation within the SolarWinds software ecosystem, which is widely used for network device configuration management and firmware updates. The vulnerability resides in the server's handling of Option Acknowledgement (OACK) packets, which are part of the TFTP protocol's optional parameters extension mechanism designed to support features like block size negotiation and timeout adjustments. The issue demonstrates how seemingly benign protocol extensions can become attack vectors when not properly validated or sanitized by network services.
The technical exploitation of this vulnerability occurs through the crafting of malicious OACK requests that contain malformed or unexpected data structures. When the vulnerable SolarWinds TFTP server processes these crafted packets, it fails to properly validate the incoming option parameters, leading to a service crash or complete shutdown of the TFTP service. This behavior aligns with CWE-121, which describes heap-based buffer overflow conditions that can result in arbitrary code execution or service disruption, though in this case the outcome is limited to denial of service rather than code execution. The flaw essentially represents a lack of proper input validation and error handling within the TFTP server's option processing logic, where the server does not adequately sanitize the data contained within the OACK packet headers before attempting to process them.
The operational impact of this vulnerability extends beyond simple service disruption, as it can affect network infrastructure management and operations that rely on TFTP for critical functions. Network administrators who depend on SolarWinds TFTP Server for device configuration backups, firmware deployments, or network monitoring may experience service interruptions that could cascade into broader network availability issues. The remote nature of the attack means that adversaries do not require physical access or local network credentials to exploit the vulnerability, making it particularly dangerous in environments where network services are exposed to untrusted networks. This vulnerability also relates to the ATT&CK technique T1499.004, which covers network denial of service attacks through service interruption, and demonstrates how protocol-level weaknesses can be leveraged to compromise availability within network infrastructure.
Mitigation strategies for CVE-2009-3115 should prioritize immediate patching of affected SolarWinds TFTP Server installations to version 9.2.0.112 or later, which contains the necessary fixes for the OACK processing logic. Network segmentation and access control measures should be implemented to limit exposure of TFTP services to untrusted networks, while monitoring systems should be configured to detect unusual TFTP traffic patterns that might indicate exploitation attempts. Additionally, administrators should consider implementing network-based intrusion detection systems that can identify malformed TFTP packets and alert on potential exploitation attempts. The vulnerability highlights the importance of proper input validation and defensive programming practices in network services, as well as the critical need for regular security updates and vulnerability assessments in enterprise network infrastructure components. Organizations should also review their TFTP usage patterns and consider migrating to more secure protocols like SFTP or TFTP over TLS when possible, as the TFTP protocol itself has inherent security limitations that make it vulnerable to various attack vectors.