CVE-2002-1063 in Jana Web Server
Summary
by MITRE
Thomas Hauck Jana Server 2.x through 2.2.1, and 1.4.6 and earlier, allows remote attackers to cause a denial of service (resource exhaustion) via a large number of FTP PASV requests, which consumes all available FTP ports.
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Analysis
by VulDB Data Team • 09/09/2025
The vulnerability described in CVE-2002-1063 represents a classic resource exhaustion attack targeting FTP server implementations. This issue affects Thomas Hauck Jana Server versions 1.x through 2.2.1 and 1.4.6 and earlier, demonstrating how seemingly benign protocol operations can be weaponized to disrupt system availability. The flaw specifically exploits the server's handling of PASV (Passive) FTP commands, which are designed to facilitate data connections between FTP clients and servers. When an attacker sends an excessive number of PASV requests, the server allocates resources for each connection attempt without proper rate limiting or connection management, leading to rapid depletion of available network ports.
The technical implementation of this vulnerability stems from inadequate resource management within the FTP server's connection handling mechanism. In passive mode, FTP servers typically open a new port for each data connection and communicate this port number to the client. The Jana Server implementation fails to properly track or limit the number of concurrent passive connections, allowing attackers to continuously request new ports without proper resource accounting. This behavior aligns with CWE-400, which categorizes resource exhaustion vulnerabilities as those that allow attackers to consume system resources through legitimate protocol operations. The vulnerability operates at the network protocol level, exploiting the fundamental FTP specification while leveraging the server's lack of defensive mechanisms against excessive connection requests.
The operational impact of this vulnerability extends beyond simple service disruption, potentially affecting system stability and availability for legitimate users. When all available FTP ports are consumed, the server becomes unable to accept new FTP connections or establish new data transfers, effectively rendering the service unusable. This resource exhaustion can cascade into broader system issues, particularly on servers handling multiple concurrent FTP sessions or those operating in environments with limited network port availability. The attack vector requires minimal sophistication and can be executed with readily available tools, making it particularly dangerous in production environments where FTP services are critical for file transfer operations. Network monitoring systems may not immediately identify this as an attack, as the behavior appears legitimate until resource exhaustion occurs.
Mitigation strategies for this vulnerability should address both immediate defensive measures and long-term architectural improvements. The most effective immediate solution involves implementing connection rate limiting and maximum connection tracking within the FTP server configuration, preventing any single client from consuming excessive resources. Network administrators should configure firewalls or IDS systems to monitor for unusual patterns of PASV requests and implement automated response mechanisms to block suspicious traffic. The server should be updated to versions that properly handle resource allocation and connection limits, as this vulnerability was addressed in later releases of the Jana Server software. Additionally, implementing proper logging and monitoring of FTP connection patterns enables administrators to detect and respond to potential attacks before they cause significant disruption. This vulnerability demonstrates the importance of implementing proper resource management and access control mechanisms as outlined in the ATT&CK framework's resource exhaustion tactics, emphasizing that network services must be designed with defensive measures against both intentional attacks and accidental resource mismanagement.