CVE-2017-18440 in cPanel
Summary
by MITRE
cPanel before 64.0.21 allows demo users to execute traceroute via api2 (SEC-244).
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Analysis
by VulDB Data Team • 07/19/2020
The vulnerability identified as CVE-2017-18440 represents a privilege escalation issue within cPanel software versions prior to 64.0.21. This flaw specifically affects demo user accounts and allows them to execute traceroute commands through the api2 interface, which constitutes a significant security risk for web hosting environments. The issue stems from inadequate access controls and input validation mechanisms within the application's API framework, particularly in how it handles demo user permissions and command execution.
The technical implementation of this vulnerability involves the api2 interface which is designed to provide programmatic access to cPanel functionality. Demo users are typically granted limited access to certain features while being restricted from executing system-level commands. However, the flaw in cPanel's permission model allows these restricted users to bypass normal access controls and invoke traceroute functionality through the api2 endpoint. This occurs because the system fails to properly validate whether the requesting user has appropriate authorization to execute network diagnostic commands, particularly those that could reveal internal network topology or be used for reconnaissance purposes.
The operational impact of this vulnerability extends beyond simple privilege escalation as it enables potential attackers to gather critical network information about the hosting environment. Traceroute commands can reveal internal IP addresses, network paths, and routing information that could be used for further exploitation or targeted attacks against the infrastructure. This information disclosure threat is particularly concerning in shared hosting environments where multiple customers' data and systems coexist on the same physical infrastructure. The vulnerability essentially provides unauthorized access to network diagnostic capabilities that should only be available to administrators or users with appropriate system privileges, creating potential attack vectors for reconnaissance and lateral movement within the hosting environment.
Security professionals should note that this vulnerability aligns with CWE-284, which addresses improper access control, and can be mapped to ATT&CK technique T1046 for network service discovery. The flaw demonstrates how insufficient input validation and access control enforcement can create unexpected capabilities for restricted user accounts. Organizations should immediately implement the vendor-provided patch for cPanel version 64.0.21 or later, which addresses the improper authorization checks in the api2 interface. Additionally, system administrators should conduct thorough audits of user permissions and access controls, particularly for demo and limited user accounts. Network monitoring should be enhanced to detect unusual traceroute activity, and regular security assessments should verify that all user accounts maintain appropriate privilege levels. The vulnerability serves as a reminder of the critical importance of proper access control implementation and the potential consequences when such controls fail in web-based management interfaces.