CVE-1999-0349 in IIS
Summary
by MITRE
A buffer overflow in the FTP list (ls) command in IIS allows remote attackers to conduct a denial of service and, in some cases, execute arbitrary commands.
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Analysis
by VulDB Data Team • 06/06/2024
The vulnerability described in CVE-1999-0349 represents a critical buffer overflow flaw within the Internet Information Services (IIS) FTP server implementation that specifically affects the LIST command functionality. This vulnerability resides in the handling of directory listing requests and demonstrates a classic stack-based buffer overflow condition that occurs when the FTP server processes maliciously crafted input data. The flaw manifests when remote attackers send specially constructed arguments to the FTP LIST command, causing the server to write beyond the allocated memory buffer boundaries and potentially overwrite adjacent memory segments including return addresses and control data structures. The vulnerability is particularly dangerous because it can be exploited by unauthenticated remote attackers who do not require valid credentials to access the FTP service.
The technical implementation of this buffer overflow stems from inadequate input validation and memory management within the IIS FTP server component. When the LIST command processes directory information, the server fails to properly bounds-check the length of user-supplied arguments before copying them into fixed-size buffers. This allows attackers to overflow the allocated memory space and manipulate the program execution flow. The vulnerability is classified under CWE-121 as a stack-based buffer overflow, which represents a well-documented weakness in software development practices that has been extensively studied in the context of exploit development and defensive programming. The attack vector operates through the standard FTP protocol on port 21, making it accessible to any network entity that can reach the vulnerable IIS server.
The operational impact of this vulnerability extends beyond simple denial of service conditions to encompass potential remote code execution capabilities. While the primary exploitation method results in service disruption, certain configurations and attack scenarios may allow adversaries to inject and execute arbitrary code on the vulnerable system with the privileges of the IIS service account. This represents a significant escalation from basic denial of service attacks to full system compromise, particularly when the IIS service operates with elevated privileges or has access to sensitive system resources. The vulnerability affects organizations running IIS versions prior to the security patches released in 1999, making it a historical example of how buffer overflow vulnerabilities can persist in enterprise environments for extended periods without proper patch management.
The exploitation of CVE-1999-0349 aligns with several tactics described in the MITRE ATT&CK framework, particularly those related to initial access and privilege escalation. Attackers can leverage this vulnerability as part of a reconnaissance phase to establish a foothold within target networks, potentially using the compromised FTP service as a launch point for further attacks. The vulnerability demonstrates how protocol-level flaws can be exploited to bypass traditional network security controls, as the attack operates at the application layer without requiring sophisticated network-level reconnaissance. Organizations should consider implementing network segmentation, disabling unnecessary FTP services, and applying immediate security patches as mitigation strategies. The incident highlights the importance of regular vulnerability assessments and the critical need for maintaining current security patches across all enterprise systems, particularly those running legacy software components that may contain known vulnerabilities. This vulnerability also underscores the necessity of input validation and proper memory management practices in software development, as recommended by secure coding guidelines and industry security standards.