CVE-2017-18394 in cPanel
Summary
by MITRE
cPanel before 68.0.15 does not have a sufficient list of reserved usernames (SEC-327).
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Analysis
by VulDB Data Team • 07/18/2020
The vulnerability identified as CVE-2017-18394 affects cPanel versions prior to 68.0.15 and stems from an insufficient list of reserved usernames within the control panel's user management system. This flaw represents a security oversight that allows unauthorized users to create accounts with names that should be protected or restricted, potentially enabling privilege escalation or system compromise. The issue is classified under CWE-1021, which deals with insufficient restriction of automated features, and specifically relates to inadequate user account management controls. When cPanel fails to properly reserve critical usernames, it creates opportunities for malicious actors to exploit the system by registering accounts that could bypass security mechanisms or gain elevated privileges.
The technical implementation of this vulnerability lies in the username validation process within cPanel's user creation functionality. The software maintains a list of reserved usernames that should be protected from user registration, but this list is incomplete or outdated, allowing attackers to register accounts with names that should remain restricted. This could include usernames that correspond to system accounts, administrative functions, or other protected identifiers that are typically reserved to prevent conflicts or security breaches. The flaw essentially creates a gap in the access control mechanism that should prevent unauthorized users from creating accounts with potentially harmful or conflicting names, thereby undermining the integrity of the user management system.
The operational impact of this vulnerability extends beyond simple account creation issues and can lead to significant security implications within cPanel environments. Attackers could potentially register accounts with reserved names that correspond to system services, database users, or administrative accounts, creating opportunities for privilege escalation or lateral movement within the system. This vulnerability aligns with ATT&CK technique T1078 which covers valid accounts and can be leveraged to establish persistence or elevate privileges. Organizations using affected cPanel versions may experience unauthorized access attempts, account hijacking, or the creation of malicious user accounts that could be used to maintain access or conduct further attacks.
Mitigation strategies for this vulnerability require immediate patching of cPanel installations to version 68.0.15 or later, which includes the corrected list of reserved usernames. System administrators should also conduct thorough audits of existing user accounts to identify any potentially malicious or unauthorized accounts that may have been created using reserved names. Additional protective measures include implementing strict user account provisioning policies, monitoring user creation activities, and reviewing the complete list of reserved usernames against industry best practices. Organizations should also consider implementing additional access controls and monitoring mechanisms to detect suspicious account creation patterns that could indicate exploitation attempts. The vulnerability demonstrates the importance of maintaining up-to-date security configurations and proper access control implementation in web-based management systems.