CVE-2015-6750 in DL FTP Server
Summary
by MITRE
Buffer overflow in Ricoh DL FTP Server 1.1.0.6 and earlier allows remote attackers to execute arbitrary code via a long USER command.
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Analysis
by VulDB Data Team • 06/02/2025
The vulnerability identified as CVE-2015-6750 represents a critical buffer overflow flaw within the Ricoh DL FTP Server version 1.1.0.6 and earlier releases. This security weakness specifically manifests when the server processes USER commands, which are fundamental components of the File Transfer Protocol communication sequence used for user authentication. The buffer overflow occurs due to inadequate input validation and bounds checking mechanisms within the server's handling of user credentials, creating an exploitable condition that can be leveraged by remote attackers to gain unauthorized system access. The vulnerability falls under the Common Weakness Enumeration category CWE-121, which specifically addresses stack-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations. This flaw directly enables attackers to execute arbitrary code on the affected system, potentially leading to complete system compromise and unauthorized data access.
The operational impact of this vulnerability extends beyond simple code execution to encompass full system control capabilities for remote attackers. When an attacker successfully exploits the buffer overflow through a carefully crafted long USER command, they can overwrite critical memory segments including return addresses and function pointers, allowing them to redirect program execution flow to malicious code. This type of exploitation aligns with the attack pattern described in the MITRE ATT&CK framework under T1059.007 for command and scripting interpreter, where adversaries leverage system vulnerabilities to execute malicious payloads. The attack surface is particularly concerning given that FTP servers are often deployed in enterprise environments where they handle sensitive data transfers, making this vulnerability a prime target for threat actors seeking persistent access to corporate networks. The vulnerability's remote nature eliminates the need for physical access or local network presence, enabling attackers to exploit it from anywhere on the internet.
Mitigation strategies for CVE-2015-6750 require immediate attention through multiple defensive layers. The most critical immediate action involves upgrading to a patched version of the Ricoh DL FTP Server software, as the vendor has released updates addressing this specific buffer overflow condition. Organizations should also implement network segmentation and firewall rules to restrict access to FTP services, limiting exposure to only trusted internal networks. Additional protective measures include deploying intrusion detection systems capable of identifying malformed USER commands and implementing strict input validation at network boundaries. The vulnerability demonstrates the importance of proper software security practices including input sanitization, bounds checking, and memory management. Security professionals should also consider implementing network monitoring solutions that can detect unusual FTP traffic patterns and establish incident response procedures specifically addressing buffer overflow exploitation attempts. Organizations utilizing legacy FTP servers should evaluate migrating to more secure protocols such as SFTP or FTPS that provide encrypted communication channels and better security controls. Regular security assessments and vulnerability scanning should be conducted to identify similar weaknesses in other network services and ensure comprehensive protection against similar attack vectors.