CVE-2017-18453 in cPanel
Summary
by MITRE
cPanel before 64.0.21 does not preserve supplemental groups across account renames (SEC-260).
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Analysis
by VulDB Data Team • 07/19/2020
The vulnerability identified as CVE-2017-18453 affects cPanel versions prior to 64.0.21 and relates to a critical flaw in how the system handles user account management during renaming operations. This issue specifically impacts the preservation of supplemental groups that are associated with user accounts, creating potential security implications within shared hosting environments where multiple users operate under the same system. The problem stems from the fact that when user accounts are renamed, the system fails to maintain the complete group membership information that users may have been assigned during their initial creation, leading to potential privilege escalation or access control bypass scenarios.
The technical root cause of this vulnerability lies in the improper handling of group context during account renaming procedures within cPanel's user management framework. When an account is renamed, the system should ensure that all associated group memberships are preserved to maintain consistent access controls and security boundaries. However, the flaw allows supplemental groups to be lost during this process, potentially leaving users with reduced privileges or, conversely, inadvertently granting them access to resources they should not possess. This behavior creates a security gap that could be exploited by malicious actors who understand the group membership implications of account renaming operations.
The operational impact of this vulnerability extends beyond simple access control issues and can significantly affect the security posture of hosting environments that rely on cPanel for user management. In shared hosting scenarios where multiple customers operate on the same server, the loss of supplemental group information during account renaming could lead to unintended privilege escalation, where users might gain access to files or directories that should be restricted to specific groups. Additionally, this vulnerability could complicate compliance requirements and audit processes, as the system's ability to maintain proper access control boundaries becomes compromised. The issue particularly affects environments where granular permissions and group-based access controls are essential for maintaining security isolation between different user accounts.
Organizations using affected cPanel versions should prioritize immediate remediation through the application of the vendor-provided patch or upgrade to version 64.0.21 or later, which addresses this specific issue by ensuring proper preservation of supplemental groups during account renaming operations. System administrators should also conduct comprehensive audits of existing user accounts to identify any potential privilege inconsistencies that may have resulted from this vulnerability. The mitigation strategy should include verification procedures to confirm that all user accounts maintain their correct group memberships following any account modifications, and security monitoring should be enhanced to detect anomalous access patterns that might indicate exploitation attempts. This vulnerability aligns with CWE-276, which addresses improper privilege management, and could potentially be leveraged by attackers following techniques outlined in the ATT&CK framework under privilege escalation and persistence tactics, particularly those involving account manipulation and access control bypass methods.