CVE-2018-20904 in cPanel
Summary
by MITRE
cPanel before 71.9980.37 allows attackers to make API calls that bypass the cron feature restriction (SEC-427).
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Analysis
by VulDB Data Team • 07/18/2020
The vulnerability identified as CVE-2018-20904 affects cPanel versions prior to 71.9980.37 and represents a critical authorization bypass flaw that undermines the platform's security controls. This issue specifically targets the cron feature restriction mechanism within cPanel's API implementation, allowing malicious actors to execute unauthorized API calls that should have been restricted. The vulnerability stems from inadequate validation of user permissions and API access controls, particularly when dealing with scheduled tasks and automated processes. Security researchers have categorized this as a privilege escalation vulnerability that enables attackers to circumvent intended security boundaries within the cPanel administrative interface.
The technical implementation flaw lies in how cPanel handles API authentication and authorization for cron-related functions. When users make API calls to manage cron jobs or related scheduled tasks, the system should enforce strict access controls to prevent unauthorized modifications or executions. However, in vulnerable versions, the authorization logic fails to properly validate whether the requesting user possesses the necessary privileges to perform certain operations. This oversight creates a pathway for attackers to exploit the system's trust model and execute commands that bypass the intended cron feature restrictions. The vulnerability operates at the application layer and can be exploited through the API interface without requiring elevated privileges or direct system access.
The operational impact of CVE-2018-20904 extends beyond simple unauthorized access, as it enables attackers to manipulate scheduled tasks and potentially execute malicious code within the cPanel environment. This vulnerability can be leveraged to modify or delete existing cron jobs, create new automated tasks that perform harmful operations, or even establish persistent backdoors through scheduled malicious scripts. The implications are particularly severe for hosting providers and organizations relying on cPanel for web hosting management, as compromised systems can lead to widespread service disruption, data compromise, and unauthorized access to multiple customer accounts. Attackers can use this vulnerability to escalate privileges within the cPanel environment, potentially gaining access to sensitive customer data, server resources, or other administrative functions.
Organizations should immediately implement the vendor-provided patch for cPanel version 71.9980.37 to remediate this vulnerability and prevent exploitation. Security teams should also conduct comprehensive audits of their cPanel installations to identify any potentially compromised systems and monitor for suspicious API activity related to cron job modifications. Additional mitigations include implementing strict API access controls, monitoring unauthorized cron job changes, and ensuring that only authorized personnel have access to administrative API endpoints. This vulnerability aligns with CWE-285, which addresses improper authorization in software systems, and can be mapped to ATT&CK techniques involving privilege escalation and persistence through scheduled tasks. Organizations should also review their network segmentation and access controls to limit potential lateral movement if exploitation occurs. The incident underscores the critical importance of maintaining up-to-date security patches and implementing robust API security measures to prevent unauthorized access to administrative functions.