CVE-2000-0800 in Linux
Summary
by MITRE
String parsing error in rpc.kstatd in the linuxnfs or knfsd packages in SuSE and possibly other Linux systems allows remote attackers to gain root privileges.
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Analysis
by VulDB Data Team • 06/07/2024
The vulnerability identified as CVE-2000-0800 represents a critical string parsing error within the rpc.kstatd daemon component of the Linux kernel's Network File System implementation. This flaw exists in the linuxnfs and knfsd packages distributed by SuSE and potentially other Linux distributions, creating a remote code execution vector that can be exploited to achieve privilege escalation to the root level. The rpc.kstatd service operates as part of the kernel-based NFS implementation and is responsible for providing system statistics and monitoring capabilities through the rpcbind service.
The technical nature of this vulnerability stems from improper handling of string parameters within the rpc.kstatd daemon when processing incoming network requests. Specifically, the flaw occurs during the parsing of user-supplied data that is passed to internal string manipulation functions without adequate bounds checking or input sanitization. This classic buffer over-read or string manipulation error allows an attacker to craft malicious network packets that, when processed by the vulnerable daemon, can overwrite critical memory locations and potentially execute arbitrary code with the privileges of the running process. The vulnerability is particularly dangerous because it operates at the kernel level where the rpc.kstatd service typically runs with elevated privileges, and the attack can be initiated remotely without authentication.
The operational impact of this vulnerability extends beyond simple privilege escalation as it provides attackers with complete control over affected systems. Once an attacker gains root privileges through this exploit, they can modify system files, install backdoors, create new user accounts, and access all data on the system. The remote nature of the attack means that an attacker can exploit this vulnerability from anywhere on the network without requiring physical access or prior authentication. Systems running vulnerable versions of the linuxnfs or knfsd packages are particularly at risk since the rpc.kstatd service is often enabled by default in many Linux distributions, making the attack surface larger than initially apparent.
This vulnerability aligns with CWE-121, which describes "Stack-based Buffer Overflow" conditions in programming environments, and specifically relates to improper input validation and string handling within network services. The attack pattern follows the MITRE ATT&CK framework's privilege escalation techniques, particularly the use of remote services to gain administrative access. Organizations running affected systems are vulnerable to both automated scanning attacks and targeted exploitation attempts, as the vulnerability affects core networking components that are frequently exposed to external network traffic. The lack of authentication requirements for exploitation makes this particularly dangerous in environments where NFS services are exposed to untrusted networks or the internet, as attackers can simply connect to the affected service and execute their malicious payloads.
The recommended mitigations include immediate patching of affected systems with updated versions of the linuxnfs or knfsd packages that contain proper input validation and string handling fixes. System administrators should disable the rpc.kstatd service if it is not actively required, as this reduces the attack surface. Network segmentation and firewall rules should be implemented to restrict access to NFS services to trusted internal networks only. Additionally, monitoring for unusual network traffic patterns and unauthorized access attempts to NFS services should be implemented as part of the overall security posture. Regular vulnerability assessments and security audits should be conducted to identify and remediate similar issues in other network services and system components that may be vulnerable to similar string parsing errors.