CVE-2019-7301 in Load Balancer
Summary
by MITRE
Zen Load Balancer 3.10.1 allows remote authenticated admin users to execute arbitrary commands as root via shell metacharacters in the index.cgi?action=View_Cert certname parameter.
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Analysis
by VulDB Data Team • 05/07/2020
The vulnerability identified as CVE-2019-7301 affects Zen Load Balancer version 3.10.1, a web-based load balancing solution designed for managing traffic distribution across multiple servers. This critical security flaw resides within the application's handling of certificate management functionality, specifically in the index.cgi script that processes administrative requests. The vulnerability is particularly concerning because it enables authenticated administrative users to escalate their privileges and execute arbitrary commands with root-level system access, fundamentally compromising the entire system integrity.
The technical exploitation mechanism centers on improper input validation within the index.cgi script where the certname parameter is processed without adequate sanitization of shell metacharacters. When an authenticated administrator accesses the View_Cert functionality and provides a specially crafted certname value containing shell injection sequences such as semicolons, ampersands, or command substitution operators, the application fails to properly escape or filter these characters before incorporating them into system commands. This classic command injection vulnerability stems from the application's direct concatenation of user-supplied input into shell execution contexts, creating an environment where malicious payloads can be interpreted and executed with the privileges of the web server process, which typically runs as root in such environments.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it provides attackers with complete system control capabilities including but not limited to arbitrary code execution, data exfiltration, system reconnaissance, and potential lateral movement within the network. Attackers can leverage this vulnerability to establish persistent backdoors, modify system configurations, access sensitive data, or use the compromised system as a launch point for further attacks against other network resources. The fact that this requires only authenticated administrative access makes it particularly dangerous in environments where administrative credentials might be compromised through phishing, credential theft, or other social engineering attacks, as the attacker can immediately escalate to full system compromise without requiring additional exploitation steps.
This vulnerability aligns with CWE-77 and CWE-78 categories within the Common Weakness Enumeration framework, specifically addressing command injection flaws where untrusted data is directly incorporated into shell commands without proper sanitization. From an adversary tactics perspective, this vulnerability maps to several ATT&CK techniques including privilege escalation through command injection and execution of malicious code with elevated privileges. The attack chain typically involves initial access through legitimate administrative credentials followed by exploitation of the command injection vulnerability to gain root access, representing a critical weakness in the application's security architecture. Organizations should implement immediate mitigations including upgrading to patched versions of Zen Load Balancer, applying input validation controls, implementing proper output encoding, and conducting comprehensive security assessments to identify similar vulnerabilities in other applications within their infrastructure.