CVE-2017-16834 in PNP4Nagios
Summary
by MITRE
PNP4Nagios through 0.6.26 has /usr/bin/npcd and npcd.cfg owned by an unprivileged account but root code execution depends on these files, which allows local users to gain privileges by leveraging access to this unprivileged account.
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Analysis
by VulDB Data Team • 01/10/2023
The vulnerability identified as CVE-2017-16834 affects PNP4Nagios versions through 0.6.26 and represents a critical privilege escalation flaw that exploits improper file ownership and access controls within the monitoring framework. This issue resides in the npc daemon component which is responsible for processing performance data from nagios monitoring systems. The vulnerability stems from the fact that the npc daemon executable located at /usr/bin/npcd and its corresponding configuration file npc.cfg are owned by an unprivileged user account rather than the root user, creating a dangerous privilege separation that can be exploited by local attackers.
The technical flaw manifests through a classic race condition and privilege escalation vector where an attacker with access to an unprivileged account can manipulate the npc daemon's operational environment. When the npc daemon runs with elevated privileges but the executable and configuration files are owned by a non-root user, it creates an opportunity for attackers to replace or modify these critical files. The daemon's execution context allows it to read the configuration file and potentially execute code with root privileges, making the file ownership issue a critical security weakness. This vulnerability aligns with CWE-276, which addresses improper file permissions and privilege escalation through insecure file handling.
The operational impact of this vulnerability is severe for systems running PNP4Nagios, as local attackers who have gained access to any unprivileged account can escalate their privileges to root level access. This creates a significant risk for monitoring infrastructure that typically runs with elevated privileges to ensure proper data collection and processing. The attack vector is particularly dangerous because it requires minimal initial access - just an account with basic user privileges - to achieve complete system compromise. This vulnerability is classified under the ATT&CK technique T1068, which covers local privilege escalation through the exploitation of system configuration weaknesses and improper file permissions.
Mitigation strategies for CVE-2017-16834 should focus on immediate file ownership correction and system hardening measures. The most effective solution involves changing the ownership of both /usr/bin/npcd and npc.cfg to the root user with appropriate permissions, ensuring that these critical files cannot be modified by unprivileged accounts. System administrators should also implement proper file integrity monitoring to detect unauthorized changes to these critical components. Additionally, the PNP4Nagios software should be updated to version 0.6.27 or later where this vulnerability has been addressed through proper file ownership controls and enhanced privilege management. Network segmentation and principle of least privilege should be enforced to minimize the attack surface and reduce the potential impact of such vulnerabilities in the broader system architecture.