CVE-2001-0696 in SurgeFTP
Summary
by MITRE
NetWin SurgeFTP 2.0a and 1.0b allows a remote attacker to cause a denial of service (crash) via a CD command to a directory with an MS-DOS device name such as con.
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Analysis
by VulDB Data Team • 10/05/2025
The vulnerability described in CVE-2001-0696 represents a classic denial of service flaw affecting NetWin SurgeFTP versions 1.0b and 2.0a. This issue stems from the FTP server's inadequate handling of specific directory names that contain MS-DOS device names such as con, prn, aux, nul, and others. The vulnerability operates at the protocol level where the FTP service fails to properly validate or sanitize directory names during command processing, particularly when executing CD (change directory) commands. When an attacker sends a CD command targeting a directory path that includes these reserved device names, the FTP server becomes vulnerable to crashing or becoming unresponsive due to improper resource management and error handling mechanisms.
The technical root cause of this vulnerability can be categorized under CWE-20, which deals with improper input validation, and specifically relates to CWE-129, improper validation of array indices, though more accurately this manifests as CWE-704, improper handling of special characters in input. The flaw occurs because the FTP server implementation does not properly distinguish between legitimate directory names and reserved MS-DOS device names that have special significance in the Windows operating system. When the server attempts to process a CD command to a directory containing these device names, it encounters a fundamental conflict in how it manages file system operations, leading to memory corruption or thread termination that results in service disruption.
From an operational impact perspective, this vulnerability presents a significant risk to organizations relying on FTP services for file transfers and data management. The denial of service condition can be easily exploited by remote attackers without requiring authentication, making it particularly dangerous in environments where FTP services are publicly accessible. The crash effect can result in complete service unavailability, forcing administrators to restart the FTP service manually and potentially disrupting legitimate user operations. This vulnerability aligns with ATT&CK technique T1499.004, which covers network denial of service attacks, and demonstrates how legacy protocols and implementations can contain fundamental design flaws that persist across multiple versions.
The exploitation of this vulnerability requires minimal technical expertise and can be accomplished through simple FTP client commands, making it a preferred target for automated attack tools. The impact extends beyond immediate service disruption as it can be used as a stepping stone for more complex attacks, particularly when combined with other vulnerabilities in the network infrastructure. Organizations with multiple FTP servers running affected versions may experience cascading failures if not properly segmented, and the vulnerability can be particularly damaging in environments where FTP services are critical for business operations. Mitigation strategies should include immediate patching of affected software versions, implementation of proper input validation mechanisms, and network segmentation to limit exposure of vulnerable FTP services to untrusted networks. Additionally, administrators should consider implementing intrusion detection systems to monitor for suspicious CD command patterns and establish robust backup and recovery procedures to minimize downtime from such attacks.