CVE-2004-0296 in Broker FTP Server
Summary
by MITRE
TsFtpSrv.exe in Broker FTP 6.1.0.0 allows remote attackers to cause a TsFtpSrv.exe to exit with an exception by opening and immediately closing a connection.
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Analysis
by VulDB Data Team • 07/08/2017
The vulnerability identified as CVE-2004-0296 affects TsFtpSrv.exe component within Broker FTP version 6.1.0.0, representing a classic denial of service weakness that exploits improper exception handling mechanisms. This flaw resides in the FTP server implementation where the service fails to properly manage connection lifecycle events, specifically when clients establish and terminate connections rapidly without transmitting any data. The vulnerability operates through a simple yet effective attack pattern where remote adversaries can trigger service instability by creating a connection to the FTP server and immediately closing it, causing the TsFtpSrv.exe process to terminate unexpectedly with an unhandled exception.
From a technical perspective, this vulnerability demonstrates poor error handling and resource management within the FTP server daemon, aligning with CWE-400 which categorizes improper exception handling as a fundamental weakness in software security design. The flaw essentially represents a race condition or state management issue where the server process does not adequately validate connection states before processing subsequent events, leading to a crash when encountering malformed or premature connection termination sequences. The immediate exit with an exception indicates that the application lacks proper defensive programming practices and robust error recovery mechanisms that would typically be expected in production-grade network services.
The operational impact of this vulnerability extends beyond simple service disruption, as it creates potential opportunities for attackers to perform systematic denial of service attacks against the FTP server infrastructure. Since the exploit requires only a single connection attempt followed by immediate closure, it can be executed rapidly and repeatedly, potentially leading to service unavailability for legitimate users. This type of vulnerability particularly affects environments where FTP services are critical for business operations or where automated systems depend on consistent service availability. The attack vector is particularly concerning as it requires minimal resources and technical expertise to execute, making it a preferred method for attackers seeking to disrupt services without complex exploitation techniques.
Organizations should implement immediate mitigations including applying available patches from the vendor, configuring firewall rules to limit connection rates, and implementing intrusion detection systems to monitor for anomalous connection patterns. The ATT&CK framework categorizes this type of vulnerability under T1499 which covers network denial of service attacks, while the broader context places it within T1566 for initial access through network services. Additional defensive measures include implementing connection throttling mechanisms, deploying service monitoring tools to detect process termination events, and establishing automated recovery procedures to minimize service downtime. System administrators should also consider implementing network segmentation to limit the attack surface and ensure that FTP services are not directly exposed to untrusted networks.