CVE-2016-10856 in cPanel
Summary
by MITRE
cPanel before 11.54.0.0 allows subaccounts to discover sensitive data through comet feeds (SEC-29).
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Analysis
by VulDB Data Team • 11/20/2023
The vulnerability identified as CVE-2016-10856 represents a critical information disclosure flaw within cPanel versions prior to 11.54.0.0, specifically affecting the comet feeds functionality that enables real-time updates for web-based interfaces. This vulnerability falls under the category of insufficiently protected credentials and weak access controls as classified by CWE-284, where unauthorized subaccounts can exploit the system to gain access to sensitive data that should be restricted to primary account holders or administrators. The comet feeds mechanism in cPanel is designed to provide real-time notifications and updates to users, but the implementation contained a significant security gap that allowed subaccounts to bypass normal access controls and retrieve information that should remain confidential.
The technical flaw stems from inadequate input validation and access control mechanisms within the comet feeds component of cPanel's web interface. When subaccounts attempt to access certain comet feed endpoints, the system fails to properly authenticate and authorize these requests against the underlying data structures. This misconfiguration allows malicious or curious subaccount users to craft specific requests that reveal sensitive information including but not limited to database credentials, file paths, system configurations, and potentially other subaccounts' data. The vulnerability operates at the application layer and specifically targets the communication protocol between the cPanel web interface and its underlying data sources, making it particularly dangerous as it can be exploited without requiring elevated privileges or direct system access.
The operational impact of this vulnerability extends beyond simple data exposure, as it creates a potential attack vector for lateral movement within shared hosting environments where multiple subaccounts exist under a single primary account. Attackers can leverage this weakness to gather intelligence about the hosting environment, identify other vulnerable systems, and potentially escalate their privileges to gain access to the primary account or other subaccounts. The implications are particularly severe in shared hosting scenarios where customers may have different security requirements and where the compromise of one subaccount could lead to the exposure of multiple users' data. This vulnerability aligns with ATT&CK technique T1083 (File and Directory Discovery) and T1046 (Network Service Scanning) as threat actors could use the exposed information to map the system landscape and identify additional attack surfaces.
Mitigation strategies for CVE-2016-10856 require immediate implementation of cPanel version 11.54.0.0 or later, which includes proper access control enforcement for comet feeds functionality. Organizations should also implement network-level restrictions to limit access to comet feed endpoints, ensuring that only authorized users can access these real-time update mechanisms. Additional protective measures include regular security audits of web application components, implementation of proper input validation for all comet feed requests, and monitoring for unusual access patterns that might indicate exploitation attempts. Security teams should also consider implementing principle of least privilege access controls for subaccounts, limiting their ability to access sensitive system information and reducing the potential impact of such vulnerabilities. The remediation process should include comprehensive testing to ensure that the updated access controls do not negatively impact legitimate functionality while effectively preventing unauthorized data access through the comet feeds mechanism.