CVE-2009-4502 in Zabbix
Summary
by MITRE
The NET_TCP_LISTEN function in net.c in Zabbix Agent before 1.6.7, when running on FreeBSD or Solaris, allows remote attackers to bypass the EnableRemoteCommands setting and execute arbitrary commands via shell metacharacters in the argument to net.tcp.listen. NOTE: this attack is limited to attacks from trusted IP addresses.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 09/21/2024
The vulnerability identified as CVE-2009-4502 represents a critical command injection flaw in the Zabbix Agent software that specifically affects systems running FreeBSD or Solaris operating systems. This vulnerability exists within the NET_TCP_LISTEN function implementation in the net.c source file, where the software fails to properly sanitize input parameters passed to the net.tcp.listen function. The flaw allows remote attackers to circumvent the security mechanism designed to prevent command execution by bypassing the EnableRemoteCommands configuration setting. The attack vector specifically targets the argument parsing within the net.tcp.listen function, where shell metacharacters can be embedded to trigger unintended command execution.
The technical implementation of this vulnerability stems from inadequate input validation and sanitization within the Zabbix Agent's network listening functionality. When the net.tcp.listen function processes arguments containing shell metacharacters such as semicolons, ampersands, or backticks, the agent fails to properly escape or filter these characters before passing them to underlying system commands. This creates an environment where malicious input can be interpreted by the shell as additional commands, effectively allowing attackers to execute arbitrary code on the target system. The vulnerability is particularly concerning because it operates at the agent level, where it can potentially escalate privileges and access sensitive system resources.
The operational impact of this vulnerability is significant, particularly in environments where Zabbix Agents are deployed with remote command execution capabilities enabled. Attackers exploiting this vulnerability can execute commands with the privileges of the Zabbix Agent process, which typically runs with elevated permissions to monitor system resources. This could enable attackers to gain unauthorized access to system files, modify monitoring configurations, or even establish persistent backdoors. The limitation to trusted IP addresses does not mitigate the risk significantly, as internal network compromise or lateral movement attacks can still lead to exploitation. The vulnerability directly violates security principles outlined in CWE-77 and CWE-78, which address command injection flaws in software systems.
Security mitigations for this vulnerability should focus on immediate patching of Zabbix Agent installations to version 1.6.7 or later, which contains the necessary input validation fixes. Network segmentation and access control measures should be implemented to restrict access to Zabbix Agents to only trusted sources, even though the vulnerability requires trusted IP addresses for exploitation. Additionally, monitoring should be enhanced to detect unusual command execution patterns or unexpected network connections originating from Zabbix Agent processes. The remediation process should include thorough review of all Zabbix Agent configurations to ensure that EnableRemoteCommands is disabled unless absolutely necessary, and that proper network access controls are in place to limit exposure to potential attackers. This vulnerability exemplifies the importance of proper input validation and the principle of least privilege in system security design.