CVE-2008-6791 in PumpKIN
Summary
by MITRE
PumpKIN TFTP Server 2.7.2.0 allows remote attackers to cause a denial of service via a write request with a long mode field.
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Analysis
by VulDB Data Team • 11/09/2024
The PumpKIN TFTP Server version 2.7.2.0 contains a critical vulnerability that enables remote attackers to execute a denial of service attack through a specially crafted write request with an excessively long mode field. This vulnerability stems from inadequate input validation within the server's handling of Trivial File Transfer Protocol operations, specifically when processing write requests from remote clients. The flaw represents a classic buffer overflow condition where the server fails to properly sanitize the mode field parameter, allowing malicious actors to submit oversized data that exceeds the allocated buffer space.
The technical implementation of this vulnerability operates at the protocol level of the TFTP service, which typically uses UDP port 69 for communication and operates with simple text-based mode specifications such as netascii, octet, or mail. When a client sends a write request to the server, it includes a mode field that specifies how the file should be transferred. The PumpKIN server implementation does not enforce reasonable bounds on this field length, creating an opportunity for attackers to submit mode strings that exceed the server's internal buffer capacity. This condition can cause the server process to crash or become unresponsive, effectively terminating its ability to serve legitimate TFTP requests.
From an operational impact perspective, this vulnerability poses significant risks to network infrastructure that relies on TFTP services for firmware updates, configuration file transfers, or other critical operations. The denial of service condition can disrupt network management processes, prevent legitimate users from accessing network resources, and potentially create opportunities for more sophisticated attacks if the server is part of a larger attack surface. The vulnerability affects any system running PumpKIN TFTP Server 2.7.2.0 regardless of platform, making it particularly concerning for organizations with multiple network devices that may be running this software.
Security professionals should consider this vulnerability in the context of the Common Weakness Enumeration framework, where it aligns with CWE-121, which describes stack-based buffer overflow conditions, and CWE-122, which addresses heap-based buffer overflow scenarios. The attack pattern also corresponds to techniques documented in the MITRE ATT&CK framework under the T1499 category for network denial of service attacks. Organizations should implement immediate mitigations including upgrading to a patched version of the PumpKIN TFTP Server software, implementing network segmentation to limit exposure, and monitoring for suspicious TFTP traffic patterns that might indicate exploitation attempts. Additionally, firewall rules can be configured to restrict TFTP access to trusted networks only, while network administrators should establish regular patch management processes to prevent similar vulnerabilities from affecting other network services.