CVE-1999-0950 in WFTPD
Summary
by MITRE
Buffer overflow in WFTPD FTP server allows remote attackers to gain root access via a series of MKD and CWD commands that create nested directories.
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Analysis
by VulDB Data Team • 10/21/2025
The vulnerability described in CVE-1999-0950 represents a critical buffer overflow flaw within the WFTPD FTP server implementation that fundamentally compromises system security through improper directory handling operations. This vulnerability specifically manifests when attackers execute a sequence of MKD and CWD commands that create deeply nested directory structures, exploiting a classic buffer overflow condition that occurs during path manipulation and directory traversal operations. The flaw resides in the server's inability to properly validate or limit the depth of nested directory creation, allowing malicious input to overwrite adjacent memory regions.
The technical exploitation of this vulnerability follows a well-established pattern that aligns with CWE-121, which describes heap-based buffer overflow conditions, and CWE-122, which addresses stack-based buffer overflow scenarios. Attackers can craft specially formatted MKD and CWD commands that incrementally build deeply nested directory paths, eventually causing the buffer allocated for path storage to overflow. This overflow corrupts the stack or heap memory, potentially allowing an attacker to overwrite return addresses, function pointers, or other critical control data structures. The vulnerability demonstrates characteristics consistent with the ATT&CK framework's technique T1059.007 for command and scripting interpreter, where attackers leverage legitimate system commands to execute malicious code through buffer overflow exploitation.
The operational impact of this vulnerability extends far beyond simple denial of service, as it provides remote attackers with the capability to escalate privileges to root access level. Once the buffer overflow occurs and memory corruption takes place, attackers can potentially redirect program execution flow to execute arbitrary code with elevated privileges, effectively compromising the entire system. The vulnerability affects systems running WFTPD server software, particularly those configured to allow directory creation and traversal operations. The exploitation requires minimal privileges to initiate the attack, making it particularly dangerous as it can be launched from any remote location without requiring authentication, thus representing a significant threat to network security infrastructure.
Mitigation strategies for this vulnerability must address both immediate defensive measures and long-term architectural improvements. Organizations should implement immediate patch management procedures to upgrade to patched versions of WFTPD software, as vendors typically released updates addressing the specific buffer overflow conditions. Network segmentation and access control measures should be enforced to limit exposure of FTP services to untrusted networks, while implementing strict input validation for all directory creation commands. The solution approach aligns with the principle of least privilege and follows ATT&CK technique T1562.001 for disabling or circumventing security tools, as proper input validation and memory management practices serve as primary defenses. Additionally, implementing intrusion detection systems to monitor for unusual MKD and CWD command sequences, along with regular security auditing and code review practices, provides comprehensive protection against similar vulnerabilities in other software components.