CVE-2018-20915 in cPanel
Summary
by MITRE
cPanel before 70.0.23 allows stored XSS via a WHM Edit DNS Zone action (SEC-369).
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Analysis
by VulDB Data Team • 07/18/2020
The vulnerability identified as CVE-2018-20915 represents a critical stored cross-site scripting flaw within cPanel software versions prior to 70.0.23. This vulnerability specifically affects the WHM Edit DNS Zone functionality, which is a core administrative component used by system administrators to manage domain name server configurations. The issue stems from inadequate input validation and output encoding mechanisms within the web interface, allowing malicious actors to inject persistent malicious scripts into DNS zone records that are subsequently executed in the context of authenticated users' browsers. The vulnerability falls under CWE-79 which categorizes cross-site scripting flaws as weaknesses in input validation and output encoding, making it particularly dangerous as it can persist across user sessions and affect multiple administrators who view the compromised DNS zone data.
The operational impact of this vulnerability extends beyond simple script execution, as it provides attackers with the ability to perform actions with the privileges of authenticated users within the cPanel environment. When system administrators access compromised DNS zone records through the WHM interface, their browsers execute the malicious scripts stored within the zone data, potentially leading to session hijacking, privilege escalation, or data exfiltration. The stored nature of this XSS vulnerability means that once the malicious payload is injected into the DNS zone, it remains active until manually removed, creating a persistent threat vector that can compromise multiple users over extended periods. This vulnerability directly aligns with ATT&CK technique T1548.002 which covers abuse of group policy or privileges, as administrators with elevated access could be compromised to perform malicious actions within the cPanel environment.
The technical exploitation of this vulnerability requires an attacker to gain access to the WHM administrative interface or find a way to inject malicious content into DNS zone records through legitimate administrative actions. Attackers can leverage this flaw to inject JavaScript code into DNS zone entries that will execute whenever any administrator views those records through the WHM interface. The vulnerability is particularly concerning in enterprise environments where multiple administrators regularly manage DNS configurations, as a single compromised zone record can affect numerous users. Security professionals should note that this vulnerability affects the broader cPanel ecosystem and requires immediate patching to prevent exploitation. Organizations should implement network segmentation and monitoring controls to detect unusual administrative activities that might indicate exploitation attempts. The remediation process involves upgrading cPanel to version 70.0.23 or later, which includes proper input sanitization and output encoding mechanisms that prevent malicious scripts from being stored or executed within the DNS zone management interface.