CVE-2006-6184 in AT-TFTP
Summary
by MITRE
Multiple stack-based buffer overflows in Allied Telesyn TFTP Server (AT-TFTP) 1.9, and possibly earlier, allow remote attackers to cause a denial of service (crash) or execute arbitrary code via a long filename in a (1) GET or (2) PUT command.
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Analysis
by VulDB Data Team • 07/11/2019
The vulnerability identified as CVE-2006-6184 represents a critical stack-based buffer overflow issue affecting Allied Telesyn TFTP Server version 1.9 and potentially earlier releases. This vulnerability resides within the file transfer protocol implementation that governs how network devices communicate and exchange data using the Trivial File Transfer Protocol. The flaw manifests when the server processes GET or PUT commands with excessively long filenames, creating a condition where memory allocated on the stack becomes overwritten beyond its intended boundaries. Such buffer overflows are particularly dangerous because they can lead to unpredictable program behavior and potentially provide attackers with opportunities to execute malicious code.
The technical exploitation of this vulnerability occurs through network-based attacks that target the TFTP server's handling of user-supplied filename data. When a remote attacker sends a specially crafted GET or PUT request containing an abnormally long filename, the server fails to properly validate the input length before copying it into a fixed-size buffer allocated on the stack. This insufficient bounds checking creates a scenario where the excessive data overflows into adjacent memory locations, potentially corrupting the stack frame and overwriting critical program execution data. The vulnerability directly maps to CWE-121 Stack-based Buffer Overflow, which is classified under the Common Weakness Enumeration framework as a fundamental flaw in memory management that occurs when data is written beyond the bounds of a stack buffer. According to the MITRE ATT&CK framework, this vulnerability would be categorized under T1190 Exploit Public-Facing Application, as it represents a weakness in a publicly accessible network service that can be leveraged for remote code execution.
The operational impact of CVE-2006-6184 extends beyond simple denial of service conditions to encompass potential system compromise and unauthorized code execution. When successfully exploited, the buffer overflow can cause the TFTP server process to crash, resulting in service disruption and denial of legitimate file transfer operations. However, more critically, the vulnerability provides attackers with a pathway to execute arbitrary code with the privileges of the TFTP server process, which typically runs with elevated system permissions. This could enable attackers to gain unauthorized access to network devices, escalate privileges, or establish persistent access points within the network infrastructure. The implications are particularly severe for network administrators who rely on TFTP servers for firmware updates, configuration file transfers, and other critical network operations, as the compromise of such services can cascade into broader network security incidents.
Mitigation strategies for CVE-2006-6184 should prioritize immediate remediation through software updates and patches provided by Allied Telesyn or third-party vendors. Organizations must conduct comprehensive inventory assessments to identify all instances of the affected TFTP server software and ensure timely deployment of security patches. Network segmentation and access controls should be implemented to limit exposure of the vulnerable service to untrusted networks, while firewall rules can be configured to restrict TFTP traffic to only necessary internal systems. Additionally, network monitoring should be enhanced to detect anomalous TFTP traffic patterns that might indicate exploitation attempts. The implementation of input validation mechanisms and bounds checking within network services can serve as defensive measures against similar vulnerabilities. Regular security assessments and vulnerability scanning should be conducted to identify and remediate similar buffer overflow conditions in other network services and applications, following industry best practices established by standards such as NIST SP 800-44 and ISO/IEC 27001 for secure network management and risk mitigation.