CVE-2001-1587 in NetWare
Summary
by MITRE
NWFTPD.nlm before 5.01w in the FTP server in Novell NetWare allows remote attackers to cause a denial of service (abend) via an anonymous STOU command.
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Analysis
by VulDB Data Team • 05/04/2026
The vulnerability described in CVE-2001-1587 affects the NWFTPD.nlm FTP server component in Novell NetWare operating systems prior to version 5.01w. This represents a classic denial of service flaw that specifically targets the file transfer protocol service running within the NetWare environment. The vulnerability is particularly concerning as it allows remote attackers to disrupt service availability without requiring authentication or privileged access to the system. The issue manifests when the server processes an anonymous STOU command, which is a standard ftp command used for storing files with unique names. This vulnerability demonstrates the importance of proper input validation and error handling in network services, as the flaw exists in the server's response to a legitimate but improperly handled command sequence.
The technical implementation of this vulnerability stems from inadequate boundary checking and error handling within the NWFTPD.nlm module. When an anonymous user sends an STOU command to the FTP server, the system fails to properly validate the command parameters or handle the resulting state transitions. This leads to an abnormal termination of the ftp server process, causing what is known as an "abend" in NetWare terminology. The flaw essentially allows an attacker to trigger a memory corruption or resource exhaustion condition that forces the server to crash and restart. From a cybersecurity perspective, this vulnerability represents a type of buffer overflow or improper state management issue that could be classified under CWE-129 or CWE-20 depending on the specific implementation details. The vulnerability's impact is amplified by the fact that it can be exploited remotely, requiring no local access or credentials, making it particularly dangerous in networked environments.
The operational impact of CVE-2001-1587 extends beyond simple service disruption to potentially compromise business continuity and availability of critical network resources. Organizations relying on Novell NetWare for file sharing and network services would face significant downtime when this vulnerability is exploited, as the FTP server would become unavailable to legitimate users. The remote nature of the attack means that organizations could be impacted by attackers located anywhere on the internet, with no geographical restrictions on exploitation. From an ATT&CK framework perspective, this vulnerability maps to the T1499.004 technique related to network denial of service attacks, specifically targeting the availability of network services. The vulnerability also demonstrates poor defensive programming practices that violate fundamental security principles, as the system should have implemented proper input sanitization and error recovery mechanisms to prevent such crashes from occurring.
Mitigation strategies for this vulnerability center around immediate patching and system updates to the NWFTPD.nlm component to version 5.01w or later. Organizations should also implement network-level controls such as firewall rules that restrict access to FTP services or limit anonymous access to the ftp server. Additionally, monitoring and logging should be enhanced to detect unusual patterns of STOU command usage that might indicate exploitation attempts. The vulnerability highlights the importance of maintaining up-to-date security patches and implementing proper access controls for network services. From a broader security perspective, this issue underscores the need for regular security assessments and vulnerability scanning to identify similar flaws in legacy systems. Organizations should also consider implementing intrusion detection systems that can identify and alert on suspicious ftp protocol activity, particularly around anonymous authentication and file transfer commands. The vulnerability serves as a reminder that even older systems require ongoing security maintenance and that remote exploitation of service flaws can have severe operational consequences.