CVE-2006-0441 in Sami FTP Server
Summary
by MITRE
Stack-based buffer overflow in Sami FTP Server 2.0.1 allows remote attackers to execute arbitrary code via a long USER command, which triggers the overflow when the log is viewed.
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Analysis
by VulDB Data Team • 08/05/2017
The vulnerability identified as CVE-2006-0441 represents a critical stack-based buffer overflow flaw in Sami FTP Server version 2.0.1 that exposes remote attackers to potential code execution capabilities. This vulnerability specifically manifests when processing the USER command, which is a fundamental authentication mechanism within the File Transfer Protocol. The flaw occurs due to insufficient input validation and bounds checking within the server's command handling routine, allowing malicious actors to craft specially formatted USER commands that exceed the allocated buffer space on the stack. When the server processes this oversized input and subsequently attempts to log or display the command for administrative purposes, the buffer overflow occurs, potentially corrupting adjacent memory locations and allowing attackers to overwrite critical program execution data.
The technical exploitation of this vulnerability follows a classic stack-based buffer overflow attack pattern that aligns with CWE-121, which categorizes stack-based buffer overflow conditions where insufficient bounds checking allows writing beyond the allocated buffer space. The attack vector requires remote network access to the FTP server, making it particularly dangerous for publicly accessible systems. When an attacker sends a USER command containing an excessive number of characters, the server's vulnerable code fails to properly validate the input length before copying it into a fixed-size stack buffer. This allows the attacker to overwrite the return address of the calling function, effectively redirecting program execution flow to malicious code injected by the attacker. The vulnerability is exacerbated by the fact that the overflow occurs during log viewing operations, meaning that even simple administrative tasks can trigger the exploit, making detection and mitigation more challenging.
The operational impact of CVE-2006-0441 extends beyond immediate code execution capabilities to encompass complete system compromise and potential lateral movement within network environments. Once successfully exploited, attackers can gain arbitrary code execution with the privileges of the FTP server process, which typically runs with elevated system permissions. This vulnerability directly maps to several tactics outlined in the MITRE ATT&CK framework, particularly the execution and privilege escalation categories, as attackers can leverage the compromised server to establish persistent access, deploy additional malware, or use the system as a launching point for further attacks against other network resources. The vulnerability's remote exploitability and lack of authentication requirements for the initial attack vector make it particularly attractive to threat actors, as it allows for automated exploitation across multiple systems without requiring prior access credentials.
Mitigation strategies for this vulnerability should encompass immediate patching of the Sami FTP Server to version 2.0.2 or later, which contains the necessary input validation fixes to prevent the buffer overflow condition. Network administrators should implement restrictive firewall rules to limit access to FTP services to only trusted sources, while also considering the complete removal of outdated FTP server software from production environments where possible. Additional defensive measures include implementing intrusion detection systems that can identify suspicious USER command patterns and monitoring for unusual log file access patterns that might indicate exploitation attempts. The vulnerability also highlights the importance of proper software security practices including input validation, bounds checking, and regular security assessments. Organizations should conduct comprehensive vulnerability assessments to identify similar buffer overflow conditions in other legacy systems and implement secure coding practices that prevent such issues from occurring in newly developed software components. Regular security updates and patch management processes should be established to ensure that known vulnerabilities are addressed promptly, as this particular flaw demonstrates the critical need for maintaining up-to-date software in network infrastructure components.