CVE-2020-28903 in Fusion
Summary
by MITRE • 05/24/2021
Improper input validation in Nagios Fusion 4.1.8 and earlier allows a remote attacker with control over a fused server to inject arbitrary HTML, aka XSS.
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Analysis
by VulDB Data Team • 05/27/2021
The vulnerability identified as CVE-2020-28903 represents a critical cross-site scripting flaw within Nagios Fusion version 4.1.8 and earlier deployments. This security weakness stems from inadequate input validation mechanisms that fail to properly sanitize user-supplied data before processing and rendering within the web interface. The affected system processes input from fused servers without sufficient sanitization, creating an avenue for malicious actors to inject arbitrary HTML content that can be executed in the context of other users' browsers.
This vulnerability operates under the Common Weakness Enumeration classification of CWE-79 which specifically addresses cross-site scripting flaws where untrusted data is improperly incorporated into web pages without adequate validation or sanitization. The attack vector requires an attacker to already possess control over a fused server within the Nagios Fusion environment, making this a privilege escalation vulnerability that leverages existing compromise to expand attack surface. The flaw enables attackers to execute malicious scripts in victims' browsers, potentially leading to session hijacking, credential theft, or further system compromise through techniques aligned with the MITRE ATT&CK framework's T1059.007 command and scripting interpreter execution tactics.
The operational impact of this vulnerability extends beyond simple data corruption or display issues, as it can facilitate complete session takeover attacks where authenticated users' browser sessions are hijacked. An attacker could inject malicious scripts that steal cookies, session tokens, or other sensitive authentication data from users interacting with the affected Nagios Fusion interface. The vulnerability's presence in fusion servers means that any compromised system within the network can serve as a launch point for injecting malicious payloads into the broader monitoring infrastructure, potentially affecting multiple users and systems that rely on the monitoring platform for security operations. The exploitation of this flaw could lead to unauthorized access to critical system information, disruption of monitoring services, and potential lateral movement within the network infrastructure.
Mitigation strategies for CVE-2020-28903 should prioritize immediate patching of Nagios Fusion installations to versions that address the input validation deficiencies. Organizations should implement comprehensive input sanitization measures at multiple layers including web application firewalls, proxy servers, and application-level defenses to prevent malicious content from reaching the vulnerable components. Network segmentation and privilege separation should be enforced to limit the potential impact of compromised fused servers, ensuring that even if one server is compromised, the attack cannot easily propagate to other critical monitoring components. Regular security assessments and penetration testing should be conducted to identify similar vulnerabilities in the monitoring infrastructure, while implementing proper access controls and monitoring for suspicious activities within the Nagios Fusion environment. Additionally, security awareness training for administrators should emphasize the importance of maintaining updated monitoring systems and understanding the attack surface presented by web-based monitoring tools.