CVE-2000-0645 in WFTPD
Summary
by MITRE
WFTPD and WFTPD Pro 2.41 allows remote attackers to cause a denial of service by using the RESTART (REST) command and writing beyond the end of a file, or writing to a file that does not exist, via commands such as STORE UNIQUE (STOU), STORE (STOR), or APPEND (APPE).
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Analysis
by VulDB Data Team • 03/19/2025
The vulnerability identified as CVE-2000-0645 affects WFTPD and WFTPD Pro version 2.41, representing a critical denial of service flaw in FTP server implementations. This vulnerability stems from improper input validation and buffer management within the file transfer protocol handling mechanisms, specifically when processing restart commands and file operations. The flaw exists in the server's ability to handle file system operations that involve seeking to specific positions within files and subsequently writing data beyond allocated boundaries or to non-existent file locations. The vulnerability manifests when attackers exploit the REST command functionality combined with various store commands including STOU, STOR, and APPE, which together create conditions where the server fails to properly validate file boundaries and write operations.
The technical exploitation of this vulnerability occurs through a combination of commands that manipulate file positioning and data writing operations within the FTP server's file system interface. When an attacker sends a REST command followed by one of the specified store commands, the server's internal file handling routines fail to properly validate the target file position or existence before proceeding with write operations. This leads to memory corruption scenarios where data is written beyond the allocated buffer space or to invalid file locations, causing the FTP service to crash or become unresponsive. The vulnerability specifically targets the server's file management subsystem and represents a classic buffer overflow condition that can be triggered through carefully crafted FTP command sequences, making it particularly dangerous as it requires minimal privileges to exploit and can be executed remotely.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise the overall availability and stability of network services. When exploited successfully, the denial of service condition can render the FTP server completely inaccessible to legitimate users, disrupting critical file transfer operations that may support business processes, backup systems, or user access to network resources. The vulnerability affects organizations that rely on WFTPD servers for file sharing and data exchange operations, potentially creating cascading effects when these services become unavailable. The attack vector is particularly concerning because it can be executed entirely through standard FTP protocol commands without requiring authentication, making it an attractive target for malicious actors seeking to disrupt services. Organizations with multiple WFTPD servers or those using the affected version in production environments face significant risk of service interruption and potential data access issues.
Mitigation strategies for this vulnerability should focus on immediate patching of affected WFTPD installations to the latest available versions that contain fixes for the buffer management and input validation issues. System administrators should implement network segmentation and access controls to limit exposure of FTP services to untrusted networks, while also monitoring for suspicious FTP command sequences that may indicate exploitation attempts. The implementation of intrusion detection systems capable of identifying malicious FTP command patterns and the deployment of network-based firewalls to restrict FTP service access can provide additional layers of protection. Organizations should also consider migrating away from the affected WFTPD implementations to more modern and secure FTP server solutions that have better memory management and input validation practices. According to CWE classification, this vulnerability maps to CWE-121, which describes heap-based buffer overflow conditions, and aligns with ATT&CK technique T1499.004 for network denial of service attacks. Regular security assessments and vulnerability scanning should be conducted to identify and remediate similar issues in other network services and applications that may exhibit comparable buffer management flaws.