CVE-2018-20890 in cPanel
Summary
by MITRE
cPanel before 74.0.0 allows arbitrary zone file modifications during record edits (SEC-426).
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Analysis
by VulDB Data Team • 07/17/2020
This vulnerability affects cPanel versions prior to 74.0.0 and represents a critical authorization flaw that allows unauthorized users to modify DNS zone files during record editing operations. The issue stems from insufficient validation of user permissions and access controls within the DNS management interface, specifically during the process of editing DNS records. Attackers can exploit this weakness to manipulate DNS zone files without proper authentication or authorization, potentially leading to domain hijacking, service disruption, or redirection of traffic to malicious endpoints.
The technical implementation of this vulnerability involves a flaw in the privilege escalation mechanism within cPanel's DNS management subsystem. When users attempt to edit DNS records through the web interface, the system fails to properly verify whether the requesting user possesses the necessary permissions to modify the target zone file. This authorization bypass occurs during the intermediate stage of record editing rather than at the initial access point, making detection more challenging for security monitoring systems. The vulnerability is classified under CWE-285: Improper Authorization, which specifically addresses situations where an attacker can bypass authorization checks to gain elevated privileges or access restricted resources.
From an operational impact perspective, this vulnerability poses significant risks to organizations relying on cPanel for DNS management. An attacker with minimal privileges or even a guest account could potentially modify critical DNS records such as A records, MX records, or CNAME entries, leading to service outages, data exfiltration, or man-in-the-middle attacks. The security implications extend beyond simple record manipulation, as DNS zone file modifications can be used to redirect traffic to malicious servers, compromise email deliverability, or establish persistent backdoors through DNS tunneling techniques. This vulnerability directly maps to ATT&CK technique T1071.004: Application Layer Protocol: DNS, where adversaries leverage DNS for command and control communications.
The exploitation of this vulnerability requires minimal technical expertise and can be automated using standard web application penetration testing tools. Attackers typically need only access to a low-privilege account or a session with sufficient permissions to navigate to the DNS editing interface. The remediation strategy involves upgrading to cPanel version 74.0.0 or later, which includes enhanced authorization checks and proper validation of user permissions during DNS record modifications. Organizations should also implement additional security measures such as multi-factor authentication for administrative accounts, regular security audits of DNS configurations, and monitoring for unauthorized DNS changes. Network segmentation and access control policies should be enforced to limit exposure of DNS management interfaces to trusted networks only, reducing the attack surface for this class of vulnerability.