CVE-2018-20940 in cPanel
Summary
by MITRE
cPanel before 68.0.27 allows attackers to read root's crontab file during a short time interval upon the enabling of backups (SEC-342).
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 07/18/2020
This vulnerability exists in cPanel versions prior to 68.0.27 and represents a critical privilege escalation and information disclosure flaw that allows attackers to access root's crontab file during a specific temporal window. The vulnerability stems from improper access controls during the backup enabling process, creating a race condition where the crontab file becomes temporarily accessible to unauthorized users. This issue falls under the CWE-284 access control weakness category, specifically manifesting as insufficient access control during system operations. The vulnerability is particularly concerning because crontab files often contain sensitive scheduled tasks, credentials, and system maintenance commands that could provide attackers with elevated privileges or system insights.
The technical implementation of this flaw occurs during the backup enabling sequence when cPanel temporarily grants access to root-level crontab files without proper authentication checks. This creates a narrow time window where attackers can exploit the system before access controls are properly enforced. The vulnerability is classified as a race condition in the ATT&CK framework under the privilege escalation tactic, specifically targeting the system configuration and credential access phases. Attackers can leverage this temporal vulnerability to extract sensitive information that may include database credentials, system access tokens, or other privileged commands that would normally be restricted to root users.
The operational impact of CVE-2018-20940 is significant as it provides attackers with access to critical system information that could facilitate further compromise. The crontab file may contain scheduled tasks that execute with root privileges, potentially exposing database connection strings, API keys, or other sensitive configuration data. This information could enable attackers to escalate privileges, maintain persistence, or conduct more sophisticated attacks against the compromised system. The vulnerability affects system administrators who rely on cPanel for hosting management, potentially compromising the security of multiple websites and services hosted on the affected system.
Mitigation strategies for this vulnerability require immediate patching of cPanel installations to version 68.0.27 or later, which addresses the race condition in the backup enabling process. System administrators should also implement monitoring for unauthorized access attempts during backup operations and consider implementing additional access controls for crontab files. The remediation process should include verifying that backup enabling processes properly enforce access controls and that temporary file permissions are correctly managed. Organizations should conduct security audits to ensure that no unauthorized access has occurred during the vulnerable time window and implement continuous monitoring solutions to detect similar temporal access control issues in other system components.