CVE-2020-28909 in Fusion
Summary
by MITRE • 05/24/2021
Incorrect File Permissions in Nagios Fusion 4.1.8 and earlier allows for Privilege Escalation to root via modification of scripts. Low-privileges users are able to modify files that can be executed by sudo.
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Analysis
by VulDB Data Team • 05/27/2021
The vulnerability identified as CVE-2020-28909 represents a critical privilege escalation flaw within Nagios Fusion versions 4.1.8 and earlier. This issue stems from improper file permission configurations that create exploitable pathways for low-privilege users to gain elevated system access. The vulnerability specifically targets the sudo execution environment where users can modify scripts that are subsequently executed with root privileges, effectively allowing unauthorized individuals to escalate their access level to the highest system privileges.
The technical root cause of this vulnerability lies in the incorrect file permissions assigned to critical system scripts within the Nagios Fusion application. When users with limited privileges can modify files that are designed to be executed through sudo commands, they exploit a fundamental security principle of least privilege. This misconfiguration allows attackers to inject malicious code into executable scripts, which then executes with elevated privileges when invoked through sudo mechanisms. The vulnerability operates under the broader category of privilege escalation attacks that leverage weak access controls and improper permission settings.
From an operational perspective, this vulnerability presents a severe risk to system integrity and security posture. Low-privilege users who can exploit this flaw can effectively bypass normal access controls and gain root access to the affected systems. This creates potential for complete system compromise, data exfiltration, and persistent backdoor establishment. The impact extends beyond individual system compromise to potentially affect entire network infrastructures if multiple systems run vulnerable versions of Nagios Fusion. The vulnerability's low severity classification belies its potential for significant damage due to the ease of exploitation and the high privileges gained.
The vulnerability aligns with several cybersecurity frameworks and threat models, including CWE-276 which addresses incorrect file permissions, and ATT&CK technique T1068 which covers privilege escalation through local exploits. Organizations using affected versions of Nagios Fusion should immediately implement mitigation strategies including updating to patched versions, reviewing and correcting file permissions, and implementing additional access controls. The recommended remediation approach includes applying vendor patches, conducting thorough permission audits, and implementing monitoring for unauthorized file modifications to prevent exploitation attempts. System administrators should also consider implementing principle of least privilege enforcement and regular security assessments to identify similar permission misconfigurations across their infrastructure.
This vulnerability demonstrates the critical importance of proper access control implementation and the potential consequences of overlooking file permission configurations in security-critical applications. The exploitation pathway represents a classic example of how seemingly minor configuration errors can create significant security risks, emphasizing the need for comprehensive security testing and regular vulnerability assessments. Organizations should prioritize patch management processes and maintain awareness of security advisories for all installed software components to prevent exploitation of similar vulnerabilities.