CVE-2000-0995 in OpenBSD
Summary
by MITRE
Format string vulnerability in OpenBSD yp_passwd program (and possibly other BSD-based operating systems) allows attackers to gain root privileges a malformed name.
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Analysis
by VulDB Data Team • 04/06/2019
The vulnerability identified as CVE-2000-0995 represents a critical format string flaw within the OpenBSD yp_passwd program, which serves as a network-based password management utility for NIS (Network Information Service) environments. This vulnerability specifically affects systems running OpenBSD and potentially other BSD-based operating systems that implement similar network services. The yp_passwd program operates as a daemon that handles password updates for users in NIS domains, making it a prime target for privilege escalation attacks due to its elevated system permissions and network accessibility.
The technical flaw manifests in the program's improper handling of user-supplied input during string formatting operations. When the yp_passwd program processes network requests containing malformed input, it fails to properly validate or sanitize the input before passing it to format string functions such as printf or sprintf. This allows attackers to inject format specifiers that can manipulate the program's execution flow and potentially execute arbitrary code with root privileges. The vulnerability stems from the program's reliance on untrusted input without proper input validation or sanitization mechanisms, creating a classic format string vulnerability that can be exploited through network-based attacks.
The operational impact of this vulnerability is severe as it provides remote attackers with a pathway to achieve complete system compromise. Attackers can exploit this vulnerability from any network location to gain root access to affected systems, effectively bypassing all normal authentication mechanisms and gaining unrestricted control over the target machine. The implications extend beyond individual system compromise as compromised systems can serve as launching points for broader network attacks, lateral movement, and persistent access within enterprise environments. This vulnerability particularly affects networked systems where NIS services are actively running and accessible from external networks.
Mitigation strategies for CVE-2000-0995 involve multiple layers of defensive measures to protect against exploitation. System administrators should immediately apply security patches released by OpenBSD and other affected vendors to address the underlying format string vulnerability. Network segmentation and access control measures should be implemented to restrict access to NIS services to trusted networks only, while disabling unnecessary NIS functionality on systems that do not require it. The principle of least privilege should be enforced by running the yp_passwd service with minimal required permissions and implementing proper input validation mechanisms. Additionally, monitoring and logging should be enhanced to detect suspicious network activity related to NIS services and potential exploitation attempts.
This vulnerability aligns with CWE-134 which specifically addresses format string vulnerabilities in software applications, and relates to ATT&CK technique T1068 which covers privilege escalation through exploitation of software vulnerabilities. The attack surface is particularly concerning in enterprise environments where NIS services are commonly deployed for centralized user management, making this vulnerability a critical concern for system administrators responsible for maintaining network security and operational integrity. The vulnerability demonstrates the importance of proper input validation and secure coding practices in network services that handle untrusted data from remote sources.