CVE-2004-0739 in Whisper FTP Surfer
Summary
by MITRE
Buffer overflow in Whisper FTP Surfer 1.0.7 allows remote FTP servers to cause a denial of service (client crash) and possibly execute arbitrary code via a long filename.
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Analysis
by VulDB Data Team • 07/07/2017
The vulnerability identified as CVE-2004-0739 represents a critical buffer overflow flaw in Whisper FTP Surfer version 1.0.7 that exposes clients to both denial of service and potential remote code execution attacks. This issue stems from inadequate input validation within the client application's handling of filename data received from remote FTP servers. The flaw manifests when the client encounters a filename exceeding the allocated buffer space during the file listing or retrieval process, creating a condition where malicious actors can craft specially crafted filenames to exploit the vulnerability.
The technical implementation of this buffer overflow occurs at the application layer where the FTP client fails to properly bounds-check filename strings before copying them into fixed-size memory buffers. When a remote FTP server sends a filename longer than the predetermined buffer capacity, the excess data overflows into adjacent memory regions, potentially corrupting critical program state information or executing arbitrary code if the overflowed data contains malicious instructions. This vulnerability operates under the CWE-121 category of stack-based buffer overflow, specifically classified as CWE-125 which describes out-of-bounds read conditions that can lead to memory corruption. The attack vector requires a remote FTP server to send a malformed filename, making it a client-side vulnerability that can be exploited through social engineering or by compromising an FTP server that serves as a relay.
The operational impact of this vulnerability extends beyond simple service disruption to potentially enable full system compromise of affected clients. A successful exploitation could result in complete system takeover, allowing attackers to execute commands with the privileges of the affected user account or even escalate to system-level access. The denial of service aspect manifests as client application crashes and system instability, while the remote code execution capability provides attackers with persistent access to compromised systems. This vulnerability aligns with ATT&CK technique T1190 which covers exploitation of remote services through buffer overflow attacks, and represents a classic example of how client-side applications can become attack vectors when they fail to validate input from untrusted sources.
Mitigation strategies for this vulnerability involve immediate patching of the Whisper FTP Surfer application to version 1.0.8 or later, which includes proper bounds checking for filename handling. System administrators should also implement network segmentation to limit exposure to potentially malicious FTP servers and consider deploying network-based intrusion detection systems to monitor for suspicious FTP traffic patterns. Additionally, users should be educated about the risks of connecting to untrusted FTP servers and the importance of keeping client applications updated. The vulnerability demonstrates the critical importance of input validation in client applications and serves as a reminder that even seemingly benign protocols like FTP can become attack vectors when client implementations lack proper security controls. Organizations should establish robust software update policies and conduct regular vulnerability assessments to identify similar flaws in other client applications that may be susceptible to similar buffer overflow conditions.