CVE-2006-0043 in nfs-server
Summary
by MITRE
Buffer overflow in the realpath function in nfs-server rpc.mountd, as used in SUSE Linux 9.1 through 10.0, allows local users to execute arbitrary code via unspecified vectors involving mount requests and symlinks.
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Analysis
by VulDB Data Team • 06/13/2019
The vulnerability identified as CVE-2006-0043 represents a critical buffer overflow flaw within the rpc.mountd service of the Network File System implementation on SUSE Linux systems. This issue specifically affects versions 9.1 through 10.0 and resides in the realpath function, which is responsible for resolving symbolic links and canonicalizing file paths. The vulnerability manifests when processing mount requests that involve symbolic links, creating an exploitable condition that can be leveraged by local attackers to execute arbitrary code with elevated privileges. The buffer overflow occurs during path resolution operations, where insufficient input validation allows maliciously crafted symlink chains to exceed allocated buffer boundaries and overwrite adjacent memory regions.
The technical exploitation of this vulnerability follows a classic buffer overflow pattern that aligns with CWE-121, which describes stack-based buffer overflow conditions. The flaw exists in the handling of user-supplied input through the mount request interface, where rpc.mountd processes symbolic links without adequate bounds checking. When a local user creates a malicious symlink structure and triggers a mount request, the realpath function fails to properly validate the length of the resolved path, allowing the overflow to occur. This vulnerability operates at the kernel level within the NFS service, making it particularly dangerous as it can be exploited to gain root privileges on the affected system. The attack vector involves local privilege escalation since the vulnerability requires only local user access to trigger the buffer overflow condition.
The operational impact of CVE-2006-0043 extends beyond simple code execution, as it provides a pathway for attackers to escalate privileges and potentially compromise entire network infrastructure. Systems running affected SUSE Linux versions become vulnerable to local attackers who can leverage this flaw to execute arbitrary commands with system-level privileges, effectively bypassing standard access controls and security mechanisms. The vulnerability is particularly concerning in multi-user environments where NFS services are active, as it allows local users to gain unauthorized access to system resources and potentially escalate to root access. This type of vulnerability can be exploited to establish persistent backdoors, modify system files, or exfiltrate sensitive data from the compromised system.
Mitigation strategies for this vulnerability should focus on immediate patching of affected SUSE Linux installations to version 10.1 or later, where the buffer overflow has been addressed through proper input validation and bounds checking in the realpath function. System administrators should also implement network segmentation to limit NFS access to trusted networks and disable unnecessary NFS services on systems where they are not required. Additional protective measures include monitoring for suspicious mount request patterns and implementing proper access controls to limit local user privileges. The vulnerability demonstrates the importance of proper input validation and memory management in system services, aligning with ATT&CK technique T1068 which covers local privilege escalation through exploitation of system vulnerabilities. Organizations should also consider implementing intrusion detection systems to monitor for exploitation attempts and maintain regular security assessments to identify similar vulnerabilities in other system components.