CVE-2004-0287 in FTP Server
Summary
by MITRE
Xlight FTP server 1.52 allows remote authenticated users to cause a denial of service (crash) via a RETR command with a long argument containing a large number of / (slash) characters, possibly triggering a buffer overflow.
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Analysis
by VulDB Data Team • 08/17/2025
The vulnerability identified as CVE-2004-0287 affects the Xlight FTP server version 1.52, presenting a significant security risk that can be exploited by remote authenticated users to execute a denial of service attack. This flaw specifically manifests when a malicious user submits a RETR command with an excessively long argument containing numerous forward slash characters. The vulnerability represents a classic buffer overflow condition that occurs during the processing of file retrieval requests, where the server fails to properly validate or limit the length of input parameters.
The technical implementation of this vulnerability stems from inadequate input validation within the FTP server's RETR command handler. When processing a RETR request with an argument containing a large number of slash characters, the server's internal buffer management becomes compromised. This condition typically arises because the application does not implement proper bounds checking on user-supplied input before attempting to process or store the data in memory. The excessive length of the argument causes memory corruption that ultimately results in the application crashing and becoming unavailable to legitimate users. This behavior aligns with CWE-121, which describes stack-based buffer overflow conditions, and CWE-122, which covers heap-based buffer overflow scenarios that can occur when insufficient bounds checking is performed.
From an operational perspective, this vulnerability creates a critical disruption to FTP services by allowing authenticated attackers to crash the server remotely. The impact extends beyond simple service interruption as it can be leveraged to deny legitimate users access to file transfer capabilities, potentially affecting business operations and data availability. The fact that this requires only authenticated access means that users who have valid credentials can exploit this weakness, making it particularly concerning for environments where user access control is not strictly enforced. The vulnerability essentially provides an attacker with a reliable method to cause service degradation without requiring elevated privileges or complex exploitation techniques.
The attack vector for this vulnerability involves a relatively simple process where an authenticated user connects to the FTP server and issues a RETR command with a specially crafted argument containing numerous slash characters. The server processes this command without proper input sanitization, leading to memory corruption and subsequent crash. This type of attack pattern aligns with the MITRE ATT&CK framework's T1499 technique for network denial of service, specifically targeting service availability through application-level attacks. Organizations should consider implementing input validation controls and establishing proper bounds checking mechanisms to prevent this type of exploitation. The vulnerability also demonstrates the importance of proper software security practices during development, particularly around handling user-supplied data and implementing robust error handling procedures.
Mitigation strategies for this vulnerability include immediate patching of the Xlight FTP server to version 1.53 or later, which contains the necessary fixes to address the buffer overflow condition. Network administrators should also implement monitoring solutions to detect unusual patterns in FTP command usage that might indicate exploitation attempts. Input validation should be strengthened at multiple layers including application-level checks and network-based filtering of suspicious command parameters. Additionally, implementing proper access controls and limiting FTP server functionality to only necessary services can reduce the attack surface. The vulnerability serves as a reminder of the critical importance of regular security updates and proper input validation in preventing denial of service attacks that can compromise system availability and service integrity.