CVE-2017-2824 in Server
Summary
by MITRE
An exploitable code execution vulnerability exists in the trapper command functionality of Zabbix Server 2.4.X. A specially crafted set of packets can cause a command injection resulting in remote code execution. An attacker can make requests from an active Zabbix Proxy to trigger this vulnerability.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 12/25/2020
The vulnerability identified as CVE-2017-2824 represents a critical code execution flaw within the Zabbix Server 2.4.x series that stems from improper input validation in the trapper command functionality. This weakness allows attackers to inject malicious commands through specially crafted packets that are processed by the server's trapper component. The vulnerability specifically affects the handling of data received from active Zabbix Proxies, which creates a unique attack vector where remote adversaries can leverage proxy communication to execute arbitrary code on the target server. The trapper functionality is designed to receive data from Zabbix proxies and process it for storage in the database, but the lack of proper sanitization creates an avenue for command injection attacks that can escalate to full system compromise. This vulnerability directly maps to CWE-77 in the Common Weakness Enumeration catalog, which classifies it as a command injection vulnerability where untrusted data is incorporated into system commands without proper validation or sanitization. The attack surface is particularly concerning because Zabbix proxies are typically deployed in network environments where they communicate with central servers, making this a potential pathway for lateral movement and persistent access within monitored networks. The vulnerability's exploitation requires minimal privileges since it leverages legitimate proxy communication channels, making it difficult to detect through traditional network monitoring approaches that might not flag the specific patterns of command injection within legitimate proxy traffic.
The technical implementation of this vulnerability occurs when the Zabbix Server processes data from active proxies through the trapper functionality, which does not adequately validate or sanitize input parameters before incorporating them into system commands. Attackers can construct malicious packets containing shell metacharacters and command injection sequences that are then executed by the server's underlying operating system. The vulnerability is particularly dangerous because it allows for arbitrary code execution with the privileges of the Zabbix Server process, which typically runs with elevated permissions to access system resources and perform monitoring tasks. The attack requires the attacker to have access to a Zabbix Proxy that is configured in active mode and communicating with the vulnerable server, but this access can often be achieved through various network reconnaissance and exploitation techniques. The command injection occurs at the system level where the Zabbix server processes the received data, bypassing application-level security controls and potentially allowing attackers to execute system commands that could include privilege escalation, data exfiltration, or system modification. This vulnerability demonstrates a classic failure in input validation and secure coding practices where the application assumes that proxy data is trusted and does not properly sanitize it before system command execution. The exploitation technique aligns with ATT&CK tactic T1059 which covers command and scripting interpreter, specifically targeting the execution of system commands through legitimate proxy communication channels.
The operational impact of CVE-2017-2824 extends beyond simple code execution to encompass potential full system compromise, data breach, and network infiltration capabilities. Once exploited, attackers can leverage the compromised Zabbix server as a foothold for further attacks within the monitored network infrastructure, potentially accessing sensitive monitoring data, system configurations, and network topology information that Zabbix typically collects. The vulnerability's exploitation can lead to persistent access through the installation of backdoors or the modification of monitoring configurations to hide malicious activities. Organizations using Zabbix Server 2.4.x are particularly at risk since this version was widely deployed in enterprise environments where the server often has elevated privileges and access to critical system information. The attack can result in unauthorized access to monitoring data, which may contain sensitive operational information, system credentials, or network configurations that could be leveraged for further attacks. Additionally, the compromised server can be used to launch attacks against other systems within the network, creating a potential attack platform for lateral movement. The vulnerability also poses risks to compliance and audit requirements since Zabbix monitoring data is often used for security auditing and compliance verification. Organizations may face regulatory violations if monitoring systems are compromised and cannot provide accurate audit trails or security event data. The impact is particularly severe in environments where Zabbix serves as a critical monitoring component for security operations centers or where it provides visibility into mission-critical systems and infrastructure. Recovery from such an attack typically involves complete system reinstallation and reconfiguration, along with thorough security audits to ensure no persistence mechanisms remain in the compromised environment.
Mitigation strategies for CVE-2017-2824 focus primarily on immediate patching of the Zabbix Server 2.4.x installations to the latest available versions that contain the necessary security fixes. Organizations should also implement network segmentation and access controls to limit which proxies can communicate with the Zabbix server, reducing the attack surface for this vulnerability. Network monitoring should be enhanced to detect anomalous proxy communication patterns that might indicate exploitation attempts, including unusual command execution patterns or unexpected data flows from proxies. The implementation of principle of least privilege should be enforced where Zabbix server processes run with minimal required permissions, limiting the potential damage from successful exploitation. Security configurations should include disabling active proxy functionality if not required for operations, and implementing strict firewall rules that limit proxy-server communication to only necessary IP addresses and ports. Regular security assessments and vulnerability scanning should include checks for outdated Zabbix server installations, particularly in environments where legacy systems may not receive regular updates. Organizations should also consider implementing intrusion detection systems that can identify command injection patterns in proxy communications and alert security teams to potential exploitation attempts. The vulnerability highlights the importance of maintaining current security patches and the risks associated with running outdated software versions in production environments, particularly for critical infrastructure monitoring systems. Additionally, organizations should conduct security training for administrators to understand the risks associated with proxy configurations and the importance of secure system administration practices. Regular security audits should verify that proxy configurations follow security best practices and that communication channels are properly secured. The vulnerability serves as a reminder of the critical importance of maintaining up-to-date security patches and the potential consequences of running vulnerable software in production environments, particularly for monitoring and security infrastructure components that serve as central points of access and control within enterprise networks.