CVE-2006-3844 in Quick N Easy FTP Server
Summary
by MITRE
Buffer overflow in Quick n Easy FTP Server 3.0 allows remote authenticated users to execute arbitrary commands via a long argument to the LIST command, a different issue than CVE-2006-2027.
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Analysis
by VulDB Data Team • 09/18/2017
The vulnerability identified as CVE-2006-3844 represents a critical buffer overflow flaw within Quick n Easy FTP Server version 3.0 that enables remote authenticated attackers to execute arbitrary code on the affected system. This security defect specifically manifests when a malicious user submits an excessively long argument to the LIST command, which is commonly used to retrieve directory listings from an ftp server. The flaw stems from inadequate input validation and bounds checking within the server's command processing mechanism, creating a pathway for attackers to overwrite adjacent memory locations and potentially gain complete control over the vulnerable system. The vulnerability differs significantly from CVE-2006-2027, which addressed a separate buffer overflow issue, indicating that this represents a distinct attack vector within the same software product.
The technical implementation of this buffer overflow occurs during the processing of the LIST command where the ftp server fails to properly validate the length of user-supplied arguments before copying them into fixed-size memory buffers. When an attacker provides an argument exceeding the allocated buffer capacity, the excess data overflows into adjacent memory regions, potentially corrupting critical program structures including return addresses, function pointers, or other control data. This memory corruption can be exploited to redirect program execution flow to malicious code injected by the attacker, effectively allowing remote code execution with the privileges of the ftp server process. The vulnerability is classified as a classic stack-based buffer overflow under CWE-121, which specifically addresses violations in which a program writes data past the end of a fixed-length buffer, and may also fall under CWE-787, which deals with out-of-bounds writes. The attack vector requires authentication to the ftp server, making it a remote authenticated vulnerability that can be particularly dangerous in environments where ftp services are exposed to untrusted networks.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with persistent access to the compromised system and potentially enables further reconnaissance and lateral movement within the network. An attacker who successfully exploits this vulnerability can execute arbitrary commands with the privileges of the ftp service account, which may have elevated permissions depending on the system configuration. The exploitation process typically involves crafting a specially formatted LIST command with an argument that exceeds the buffer capacity by a calculated amount, allowing the attacker to overwrite the return address on the stack and redirect execution to their malicious payload. This vulnerability directly aligns with techniques described in the attack pattern taxonomy under ATT&CK tactic TA0002 (Execution) and TA0003 (Persistence), as it enables both command execution and potential long-term access to the compromised system. The vulnerability affects systems where Quick n Easy FTP Server version 3.0 is deployed, particularly those that expose ftp services to external networks without proper network segmentation or access controls.
Mitigation strategies for CVE-2006-3844 should prioritize immediate patching of the vulnerable software to address the buffer overflow condition in the LIST command implementation. Organizations should implement network segmentation to limit access to ftp services, restrict ftp access to trusted networks only, and enforce strong authentication mechanisms to reduce the attack surface. Additional defensive measures include deploying intrusion detection systems to monitor for suspicious LIST command patterns, implementing input validation at network boundaries, and conducting regular vulnerability assessments to identify similar issues in other ftp server implementations. System administrators should also consider disabling unnecessary ftp services, implementing proper access controls and logging mechanisms, and establishing network monitoring procedures to detect potential exploitation attempts. The vulnerability highlights the importance of secure coding practices in network services, particularly around input validation and memory management, and underscores the need for regular security updates and patch management processes to address known vulnerabilities in third-party software components.