CVE-2017-14312 in Nagios
Summary
by MITRE
Nagios Core through 4.3.4 initially executes /usr/sbin/nagios as root but supports configuration options in which this file is owned by a non-root account (and similarly can have nagios.cfg owned by a non-root account), which allows local users to gain privileges by leveraging access to this non-root account.
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Analysis
by VulDB Data Team • 12/28/2022
The vulnerability identified as CVE-2017-14312 affects Nagios Core versions through 4.3.4 and represents a privilege escalation flaw that stems from improper file ownership handling during the application's initialization process. This issue occurs when the Nagios service executes with root privileges initially but can be configured to run with non-root credentials, creating a security gap that local attackers can exploit to elevate their privileges. The vulnerability is particularly concerning because it leverages the legitimate configuration flexibility of Nagios while introducing an unexpected security risk through file ownership mismanagement.
The technical flaw manifests in the way Nagios Core handles file ownership during its startup sequence. When the system initializes, Nagios executes the main binary at /usr/sbin/nagios with root privileges, which is standard behavior for services requiring elevated access to perform monitoring functions. However, the application's configuration allows administrators to specify that the nagios binary and its configuration file nagios.cfg can be owned by non-root accounts. This configuration option, while intended to provide flexibility and security through privilege separation, creates a race condition or access control vulnerability that attackers can manipulate. The flaw exists because the application does not properly validate or enforce the security implications of these non-root ownership configurations, allowing local users with access to the non-root account to potentially escalate privileges.
The operational impact of this vulnerability is significant for systems running Nagios Core in environments where local user access cannot be fully controlled or where privilege separation is not properly enforced. Attackers with access to a non-root account that owns the Nagios binary or configuration files can exploit this weakness to gain root privileges, effectively compromising the entire monitoring infrastructure. This privilege escalation allows attackers to execute arbitrary code with full system privileges, potentially leading to complete system compromise. The vulnerability is particularly dangerous in multi-tenant environments or shared systems where local users might have access to the Nagios service accounts but should not possess root-level access. The impact extends beyond immediate privilege escalation to include potential data exfiltration, system modification, and further lateral movement within the network.
Mitigation strategies for this vulnerability should focus on proper file ownership and access control enforcement. System administrators should ensure that the Nagios binary and configuration files are owned by the root user or a dedicated non-root account with appropriate permissions, rather than allowing arbitrary ownership configurations that could be exploited. The recommended approach involves implementing strict file ownership policies where the nagios binary and configuration files maintain root ownership and proper permissions. Additionally, organizations should review their Nagios configurations to eliminate any settings that permit non-root ownership of critical files. Security best practices suggest implementing the principle of least privilege by ensuring that service accounts have minimal necessary permissions. This vulnerability aligns with CWE-276, which addresses improper file permissions, and relates to ATT&CK technique T1068, privilege escalation through local exploitation. Regular security audits and monitoring of file ownership changes can help detect potential exploitation attempts, while implementing proper access controls and privilege separation mechanisms can prevent this specific attack vector from being successfully exploited.