CVE-2001-0695 in WFTPD
Summary
by MITRE
WFTPD 3.00 R5 allows a remote attacker to cause a denial of service by making repeated requests to cd to the floppy drive (A:\).
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Analysis
by VulDB Data Team • 05/17/2019
The vulnerability identified as CVE-2001-0695 affects WFTPD version 3.00 R5, a Windows FTP server implementation that was widely deployed in enterprise environments during the early 2000s. This particular flaw represents a classic denial of service vulnerability that exploits the server's handling of specific file system operations. The vulnerability is particularly concerning because it can be triggered remotely without requiring authentication, making it accessible to any attacker with network connectivity to the affected system. The flaw specifically manifests when a remote attacker sends repeated commands to change directory to the floppy drive letter A:, which represents a fundamental system resource that should not be directly accessible through FTP operations.
The technical root cause of this vulnerability lies in the improper input validation and resource handling within the WFTPD server's directory change functionality. When the server receives a cd command targeting the A: drive, it fails to properly validate the request or handle the operation gracefully. This leads to a condition where repeated requests cause the server to enter an infinite loop or consume excessive system resources, ultimately resulting in the service becoming unresponsive. The vulnerability operates at the application layer and leverages the protocol's lack of proper error handling for invalid or unsupported directory operations. This issue is classified under CWE-400 as an Uncontrolled Resource Consumption, specifically manifesting as a denial of service condition that exhausts server resources through malformed requests.
The operational impact of this vulnerability extends beyond simple service disruption, as it can be exploited to render critical file transfer services unavailable to legitimate users. In enterprise environments where FTP services were commonly used for file distribution, data backup operations, or system administration tasks, this vulnerability could have significant business implications. The remote nature of the attack means that adversaries could exploit the flaw from anywhere on the network, potentially leading to extended service outages that affect multiple users and applications dependent on the FTP service. This type of vulnerability aligns with ATT&CK technique T1499.004, which covers Network Denial of Service attacks that target services to make them unavailable to users.
Mitigation strategies for this vulnerability include immediate patching of the WFTPD software to the latest available version that addresses the directory handling issue. Organizations should also implement network-level controls such as firewall rules that restrict access to FTP services from untrusted networks and consider deploying intrusion detection systems that can identify and block repeated malformed requests targeting the vulnerable functionality. Additionally, system administrators should monitor FTP server logs for unusual patterns of directory change requests and implement rate limiting to prevent the exploitation of this vulnerability through automated attack tools. The vulnerability demonstrates the importance of proper input validation and resource management in network services, highlighting how seemingly benign operations can be exploited to cause significant service disruption when not properly secured against malformed inputs.