CVE-2017-18437 in cPanel
Summary
by MITRE
cPanel before 64.0.21 allows a Webmail account to execute code via forwarders (SEC-240).
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Analysis
by VulDB Data Team • 07/19/2020
The vulnerability CVE-2017-18437 represents a critical code execution flaw in cPanel versions prior to 64.0.21 that specifically affects webmail account functionality through forwarder configurations. This vulnerability falls under the category of insecure input handling and privilege escalation, with implications for web application security and email system integrity. The issue stems from insufficient validation of user-supplied data within the forwarder functionality, creating a pathway for malicious actors to inject and execute arbitrary code on the affected system.
The technical exploitation occurs when a webmail account user manipulates forwarder configurations to include malicious payload within the forwarder settings. This flaw enables an authenticated attacker with webmail account access to potentially escalate privileges and execute commands with the privileges of the web server or cPanel service account. The vulnerability is particularly dangerous because it leverages legitimate webmail functionality to bypass normal security controls, making detection more challenging. The attack vector specifically targets the forwarder component which is commonly used for email routing and redirection within cPanel environments.
From an operational impact perspective, this vulnerability poses significant risk to organizations relying on cPanel for web hosting and email services. Successful exploitation could result in complete system compromise, data exfiltration, and unauthorized access to multiple user accounts. The vulnerability affects the core email infrastructure of cPanel installations, potentially allowing attackers to establish persistent access, deploy malware, or conduct further reconnaissance within the network. Organizations with multiple cPanel installations would face widespread impact if this vulnerability is present across their hosting infrastructure.
The mitigation strategy involves immediate patching of cPanel installations to version 64.0.21 or later, which includes proper input validation and sanitization for forwarder configurations. Security administrators should also implement network monitoring to detect unusual forwarder configuration changes and establish strict access controls for webmail accounts. Additional defensive measures include disabling unnecessary email forwarding features where possible, implementing robust user authentication mechanisms, and conducting regular security audits of email system configurations. This vulnerability aligns with CWE-74 and CWE-89 categories related to injection flaws and improper input validation, and maps to ATT&CK techniques involving privilege escalation and command execution through web applications. Organizations should also review their incident response procedures to address potential exploitation of this vulnerability in their hosting environments.