CVE-2000-0856 in SunFTP
Summary
by MITRE
Buffer overflow in SunFTP build 9(1) allows remote attackers to cause a denial of service or possibly execute arbitrary commands via a long GET request.
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Analysis
by VulDB Data Team • 10/12/2025
The vulnerability identified as CVE-2000-0856 represents a critical buffer overflow flaw within SunFTP version build 9(1) that exposes systems to remote exploitation. This vulnerability specifically manifests during the processing of GET requests, where the ftp server fails to properly validate input length before attempting to store data in allocated memory buffers. The flaw stems from inadequate bounds checking mechanisms that allow attackers to craft malicious requests exceeding the intended buffer capacity, leading to memory corruption and potentially arbitrary code execution.
The technical implementation of this vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions where insufficient boundary checking permits data to overwrite adjacent memory locations. When a remote attacker submits a specially crafted GET request containing excessive data, the ftp server's input handling routine fails to enforce proper length limitations, causing the buffer to overflow and overwrite critical memory segments including return addresses and program control structures. This memory corruption can result in unpredictable program behavior, system crashes, or in more severe cases, allow attackers to inject and execute malicious code within the target system's memory space.
From an operational perspective, this vulnerability presents significant risks to organizations relying on SunFTP services, as it enables remote attackers to either cause denial of service through system crashes or potentially gain complete system compromise. The attack vector requires no authentication, making it particularly dangerous as it can be exploited from any network location. The impact extends beyond simple service disruption, as successful exploitation could allow attackers to execute arbitrary commands with the privileges of the ftp service account, potentially leading to full system compromise and unauthorized access to sensitive data stored on the affected servers.
The mitigation strategies for CVE-2000-0856 should prioritize immediate patch deployment from Sun Microsystems to address the buffer overflow vulnerability in the ftp server implementation. Organizations should also implement network segmentation and access controls to limit exposure of ftp services to trusted networks only, while monitoring for suspicious GET request patterns that may indicate attempted exploitation. Additionally, regular security audits should verify that all ftp server implementations properly validate input lengths and enforce appropriate buffer size limitations to prevent similar vulnerabilities from occurring in other components of the system infrastructure. This vulnerability demonstrates the critical importance of proper input validation and memory management practices in network service implementations, aligning with ATT&CK technique T1203 for exploitation of software vulnerabilities to achieve remote code execution.