CVE-2018-20922 in cPanel
Summary
by MITRE
cPanel before 70.0.23 allows stored XSS via a WHM DNS Cleanup action (SEC-376).
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Analysis
by VulDB Data Team • 07/18/2020
The vulnerability identified as CVE-2018-20922 represents a critical stored cross-site scripting flaw within cPanel software versions prior to 70.0.23. This security weakness specifically manifests within the WHM DNS Cleanup action functionality, where malicious input can be persistently stored and subsequently executed when unsuspecting users interact with the affected interface. The vulnerability falls under the category of CWE-79 - Improper Neutralization of Input During Web Page Generation, which is a fundamental web application security concern that enables attackers to inject malicious scripts into web pages viewed by other users.
The technical implementation of this vulnerability occurs when administrators or users perform DNS cleanup operations through the WHM interface without proper input sanitization. Attackers can craft malicious payloads that get stored within the cPanel system's DNS records or related data structures. When other users subsequently access the DNS cleanup interface or related pages, these stored scripts execute in their browsers, potentially leading to session hijacking, credential theft, or further exploitation of the compromised systems. The stored nature of this XSS vulnerability means that the malicious code persists even after the initial injection point, making it particularly dangerous as it can affect multiple users over extended periods.
The operational impact of this vulnerability extends beyond simple script execution, as it can enable attackers to escalate privileges within the cPanel environment and potentially gain unauthorized access to sensitive system information. The WHM DNS Cleanup action typically involves administrative functions that require elevated privileges, making successful exploitation particularly concerning for system administrators who may inadvertently trigger the malicious code during routine maintenance operations. This vulnerability directly impacts the integrity and confidentiality of cPanel installations, potentially allowing attackers to access DNS configurations, user accounts, and other sensitive administrative data.
Organizations should immediately upgrade to cPanel version 70.0.23 or later to remediate this vulnerability, as the update includes proper input validation and sanitization measures for the affected WHM DNS Cleanup functionality. Additional mitigations include implementing strict input validation at multiple layers, enabling content security policies to prevent unauthorized script execution, and conducting regular security audits of administrative interfaces. From an ATT&CK framework perspective, this vulnerability aligns with T1059.005 - Command and Scripting Interpreter: Visual Basic, as it enables attackers to execute malicious scripts within user browsers, and T1547.001 - T1547.001 - Registry Run Keys / Startup Folder, as it can be leveraged to establish persistent access through browser-based attacks. Security teams should also consider implementing web application firewalls and monitoring for suspicious input patterns in administrative interfaces to detect potential exploitation attempts.