CVE-2018-20889 in cPanel
Summary
by MITRE
cPanel before 74.0.0 allows certain file-read operations via password file caching (SEC-425).
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Analysis
by VulDB Data Team • 07/17/2020
The vulnerability identified as CVE-2018-20889 affects cPanel versions prior to 74.0.0 and represents a critical file read flaw that exploits password file caching mechanisms. This issue falls under the category of insecure direct object reference vulnerabilities and specifically targets the way cPanel handles authentication caching for password files. The vulnerability allows unauthorized users to perform file read operations that should typically be restricted to authenticated administrators, creating a significant security risk for hosting environments that rely on cPanel for server management.
The technical flaw manifests through the improper handling of cached password files within cPanel's authentication system. When cPanel processes authentication requests, it caches certain password-related information to improve performance and reduce database load. However, this caching mechanism fails to properly validate access permissions for the cached files, allowing malicious actors to exploit the system by crafting specific requests that bypass normal authentication checks. The vulnerability specifically impacts the SEC-425 security module, which is responsible for managing authentication caching processes and password file handling. This weakness enables attackers to read sensitive files that contain authentication credentials, user information, and other confidential data stored in password cache files.
The operational impact of this vulnerability extends far beyond simple unauthorized file access, as it fundamentally undermines the authentication security model of cPanel installations. Attackers can leverage this flaw to obtain administrative credentials, user account information, and potentially gain access to multiple systems within a hosting environment. The vulnerability affects organizations running older cPanel versions, particularly those that have not updated to the 74.0.0 release or later, creating widespread exposure across hosting providers and enterprise environments. This issue directly violates security principles outlined in the OWASP Top 10, specifically addressing the weakness of insecure authentication mechanisms and improper access control. The impact is particularly severe in shared hosting environments where multiple customers' data resides on the same infrastructure, as a successful exploitation could lead to data breaches, privilege escalation, and unauthorized access to customer accounts.
Mitigation strategies for CVE-2018-20889 require immediate action to upgrade cPanel installations to version 74.0.0 or later, which includes patches addressing the password file caching vulnerability. Organizations should also implement network segmentation and access controls to limit exposure of cPanel interfaces, while monitoring for suspicious authentication attempts and file access patterns. Security teams should conduct comprehensive audits of their cPanel installations to identify any systems running vulnerable versions and ensure proper patch management processes are in place. Additional defensive measures include implementing web application firewalls to detect and block malicious requests targeting authentication mechanisms, while also reviewing system logs for evidence of unauthorized access attempts. The vulnerability aligns with ATT&CK technique T1078 for valid accounts and T1566 for credential access, making it a critical target for both preventive and detective security controls. Organizations should also consider implementing multi-factor authentication and privileged access management solutions to reduce the impact of potential credential compromise. Regular security assessments and vulnerability scanning should be conducted to ensure ongoing protection against similar authentication-related vulnerabilities in hosting environments.