CVE-2006-2226 in XM Easy Personal FTP Server
Summary
by MITRE
Buffer overflow in XM Easy Personal FTP Server 4.2 and 5.0.1 allows remote authenticated users to cause a denial of service via a long argument to the PORT command.
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Analysis
by VulDB Data Team • 06/17/2024
The vulnerability identified as CVE-2006-2226 represents a critical buffer overflow flaw within XM Easy Personal FTP Server versions 4.2 and 5.0.1 that exposes the system to remote authenticated denial of service attacks. This vulnerability specifically targets the PORT command implementation within the FTP server software, where insufficient input validation allows maliciously crafted arguments to trigger memory corruption. The flaw exists at the protocol handling layer where the server fails to properly validate the length of arguments passed to the PORT command, creating an opportunity for attackers to exploit memory boundaries and cause unintended program behavior. Such buffer overflow conditions fall under the CWE-121 category of stack-based buffer overflow, where data written to a fixed-length buffer exceeds its allocated space. The vulnerability operates within the context of the File Transfer Protocol (FTP) standard, which relies on specific command sequences for establishing data connections between client and server components. When an authenticated user submits a specially crafted long argument to the PORT command, the server processes this input without adequate bounds checking, leading to memory corruption that typically results in application crash or system instability. This particular implementation flaw demonstrates a failure in input sanitization and boundary checking mechanisms that are fundamental requirements for secure network service implementations.
The operational impact of this vulnerability extends beyond simple service disruption as it enables authenticated attackers to systematically degrade the availability of the FTP service through controlled denial of service attacks. Attackers can leverage this weakness to repeatedly send malformed PORT commands, causing the FTP server to crash and restart, thereby creating persistent service interruptions that affect legitimate users. The vulnerability is particularly concerning because it requires only authenticated access to exploit, meaning that users with valid credentials can trigger the denial of service condition without requiring additional privileges or complex attack vectors. The attack surface is limited to the specific FTP command interface, but the consequences are severe as the service disruption affects all users of the FTP server. This vulnerability directly relates to the ATT&CK technique T1499.004 which involves network denial of service attacks targeting services and protocols. The exploitation process involves crafting a specific payload that exceeds the buffer capacity, causing memory corruption that leads to process termination. The server's inability to handle malformed input gracefully demonstrates a lack of proper error handling and input validation that should be implemented according to secure coding practices and industry standards such as those outlined in the OWASP Secure Coding Practices. The vulnerability also represents a failure in the principle of least privilege as the authenticated user can leverage their access to cause system-wide service disruption rather than being limited to their intended access scope.
Mitigation strategies for CVE-2006-2226 should focus on immediate software updates and patches provided by the vendor to address the buffer overflow condition in the FTP server implementation. System administrators should ensure that all instances of XM Easy Personal FTP Server are updated to versions that contain proper input validation and boundary checking for the PORT command. Additionally, network segmentation and access controls should be implemented to limit the scope of authenticated users who can interact with the FTP service, reducing the potential attack surface. The implementation of intrusion detection systems that monitor for unusual PORT command patterns can provide early warning of exploitation attempts. Regular security assessments and vulnerability scanning should be conducted to identify similar buffer overflow conditions in other network services. Organizations should also implement proper logging and monitoring of FTP server activities to detect anomalous behavior that may indicate exploitation attempts. The fix should include comprehensive input validation that checks argument lengths against predefined maximum limits and implements proper error handling that prevents memory corruption from occurring. This vulnerability underscores the importance of secure coding practices and the necessity of thorough testing for buffer overflow conditions in all network service implementations. The remediation process should also involve reviewing other FTP commands for similar vulnerabilities and implementing defensive programming techniques such as stack canaries and address space layout randomization to provide additional protection against similar attacks. Network administrators should consider implementing rate limiting and connection throttling mechanisms to prevent exploitation attempts from overwhelming the service. The vulnerability serves as a reminder of the critical need for maintaining up-to-date security patches and the importance of conducting regular security assessments to identify and remediate potential weaknesses in network infrastructure components.