CVE-2017-18387 in cPanel
Summary
by MITRE
cPanel before 68.0.15 allows arbitrary code execution via Maketext injection in a Reseller style upload (SEC-314).
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Analysis
by VulDB Data Team • 07/18/2020
The vulnerability CVE-2017-18387 represents a critical arbitrary code execution flaw in cPanel versions prior to 68.0.15, specifically exploiting a Maketext injection vulnerability within the Reseller style upload functionality. This issue falls under the CWE-94 category of Code Injection, where malicious input is processed as executable code rather than data, creating a pathway for attackers to execute arbitrary commands on the affected system. The vulnerability stems from insufficient input validation and sanitization mechanisms within the Reseller style upload feature, which processes user-supplied data without proper security checks.
The technical exploitation occurs when a malicious actor uploads a specially crafted Reseller style file that contains Maketext injection payloads. These payloads leverage the way cPanel processes template variables and user input within the upload handling mechanism. The vulnerability is particularly dangerous because it allows attackers to bypass normal authentication and authorization controls, enabling them to execute arbitrary code with the privileges of the web server process. This creates a significant escalation path from a simple upload functionality to full system compromise.
The operational impact of this vulnerability extends beyond immediate code execution capabilities, as it provides attackers with persistent access to the compromised system. Once exploited, attackers can establish backdoors, exfiltrate sensitive data, modify system configurations, or use the compromised server as a launch point for further attacks within the network. The vulnerability affects cPanel installations where the Reseller functionality is enabled, making it particularly concerning for hosting providers and organizations that rely on cPanel for their web hosting infrastructure. The attack surface is broadened by the fact that many cPanel installations allow reseller accounts to upload custom styles, making this exploitation vector accessible to users with relatively low privileges.
Mitigation strategies for CVE-2017-18387 primarily focus on immediate patching of cPanel to version 68.0.15 or later, which addresses the underlying Maketext injection vulnerability. Organizations should also implement network-level restrictions to limit access to cPanel upload functionality, particularly for reseller accounts. Additional security measures include implementing strict input validation for all uploaded files, monitoring upload activities for suspicious patterns, and applying principle of least privilege access controls to reseller accounts. The vulnerability demonstrates the importance of proper template processing security and aligns with ATT&CK technique T1059.001 for command and script injection, as well as T1566 for social engineering through phishing or malicious file uploads. Organizations should also consider implementing web application firewalls to detect and block malicious upload attempts, and conduct regular security audits to identify similar injection vulnerabilities in other components of their hosting infrastructure.