CVE-2016-5764 in Rumba FTP
Summary
by MITRE
Micro Focus Rumba FTP 4.X client buffer overflow makes it possible to corrupt the stack and allow arbitrary code execution. Fixed in: Rumba FTP 4.5 (HF 14668). This can only occur if a client connects to a malicious server.
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Analysis
by VulDB Data Team • 05/26/2025
The vulnerability identified as CVE-2016-5764 represents a critical buffer overflow flaw within the Micro Focus Rumba FTP 4.X client software that exposes users to significant security risks. This issue stems from improper input validation mechanisms within the FTP client implementation, specifically when processing data from remote servers during connection establishment and file transfer operations. The flaw manifests as a classic stack-based buffer overflow condition that can be exploited by malicious actors who control the FTP server to which the vulnerable client connects.
The technical nature of this vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations including return addresses and control data. The exploit requires a malicious FTP server to be compromised or controlled by an attacker, as the vulnerability only triggers when the vulnerable client establishes a connection to such a server. During normal operation, the client processes server responses without adequate boundary checks, allowing an attacker to craft specially formatted responses that exceed the allocated buffer space and corrupt the program's execution stack.
From an operational perspective, this vulnerability presents a sophisticated attack vector that leverages the trust relationship inherent in FTP client-server communications. The attack scenario requires the victim user to connect to a compromised FTP server, which then serves maliciously crafted data that triggers the buffer overflow. This makes the vulnerability particularly dangerous in environments where users may connect to untrusted or compromised FTP servers, such as public FTP repositories or servers that have been breached by attackers. Successful exploitation can lead to complete system compromise, allowing attackers to execute arbitrary code with the privileges of the affected user, potentially enabling lateral movement within networks or persistence mechanisms.
The remediation for this vulnerability involves upgrading to Micro Focus Rumba FTP 4.5 with Hotfix 14668, which implements proper input validation and buffer management techniques to prevent the overflow condition. Security professionals should also consider implementing network segmentation and access controls to limit exposure to untrusted FTP servers, alongside monitoring for suspicious FTP connections and implementing secure FTP protocols such as SFTP or FTPS to reduce the attack surface. This vulnerability demonstrates the importance of proper input validation and memory management practices in client software, particularly in applications that process data from untrusted sources, and aligns with ATT&CK technique T1059.007 for execution through command and scripting interpreter. Organizations should prioritize this update as part of their vulnerability management programs and consider conducting security assessments to identify other potentially vulnerable FTP client implementations within their environments.