CVE-2014-5211 in Reflection FTP Client
Summary
by MITRE
Stack-based buffer overflow in the Attachmate Reflection FTP Client before 14.1.433 allows remote FTP servers to execute arbitrary code via a large PWD response.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 06/19/2017
The CVE-2014-5211 vulnerability represents a critical stack-based buffer overflow flaw in the Attachmate Reflection FTP Client software versions prior to 14.1.433. This vulnerability resides in the client's handling of FTP server responses, specifically when processing the PWD (Print Working Directory) command response. The flaw occurs when a remote FTP server sends an oversized PWD response that exceeds the allocated buffer space in the client application's memory stack, creating a condition where attacker-controlled data can overwrite adjacent memory locations. This type of vulnerability falls under the CWE-121 category of stack-based buffer overflow, which is classified as a serious security weakness that can lead to arbitrary code execution.
The technical implementation of this vulnerability exploits the fundamental flaw in input validation within the FTP client's protocol handling mechanism. When the Reflection FTP Client receives a PWD response from a malicious FTP server, it fails to properly validate the length of the response data against the predetermined buffer size. The buffer overflow occurs because the application does not implement bounds checking or length validation before copying the server response into a fixed-size stack buffer. This allows an attacker to craft a specially formatted PWD response that contains more data than the allocated buffer can accommodate, causing the excess data to overwrite adjacent memory locations including return addresses and control data. The vulnerability is particularly dangerous because it can be triggered through a simple FTP server interaction without requiring any special privileges or user interaction, making it a remote code execution vulnerability that aligns with ATT&CK technique T1203 for Exploitation for Execution.
The operational impact of CVE-2014-5211 extends beyond simple code execution capabilities to encompass complete system compromise and data exfiltration scenarios. An attacker who successfully exploits this vulnerability can gain full control over the victim machine running the vulnerable FTP client, potentially leading to unauthorized access to sensitive corporate data, system reconnaissance, and establishment of persistent backdoors. The attack vector is particularly concerning because it operates at the application layer of the network stack, allowing exploitation through standard FTP connections without requiring specialized network access or complex attack chains. Organizations using the affected Reflection FTP Client software face significant risk exposure, especially in environments where employees regularly connect to external FTP servers or where the client is used in automated processes that interact with untrusted FTP services. The vulnerability's classification as a remote code execution flaw means that attackers can potentially compromise systems from anywhere on the network without requiring physical access or local user privileges.
Mitigation strategies for CVE-2014-5211 focus primarily on immediate software updates and network security controls. The most effective remediation involves upgrading the Attachmate Reflection FTP Client to version 14.1.433 or later, which includes proper input validation and buffer size enforcement mechanisms. Organizations should also implement network segmentation and firewall rules that restrict access to FTP servers from untrusted networks, particularly when using FTP clients that may be vulnerable to such attacks. Additional protective measures include deploying network-based intrusion detection systems that can monitor for suspicious FTP response patterns and implementing application whitelisting policies to restrict execution of vulnerable FTP client applications. Security teams should also consider disabling unnecessary FTP client functionality and implementing strict input validation at network boundaries to prevent malformed responses from reaching vulnerable applications. The vulnerability's exploitation potential makes it essential for organizations to conduct comprehensive vulnerability assessments to identify all systems running affected software versions and to establish incident response procedures for potential exploitation attempts.