CVE-2018-16236 in cPanel
Summary
by MITRE
cPanel through 74 allows XSS via a crafted filename in the logs subdirectory of a user account, because the filename is mishandled during frontend/THEME/raw/index.html rendering.
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Analysis
by VulDB Data Team • 03/19/2020
This vulnerability exists within cPanel version 74 and earlier, where improper handling of user-supplied filenames in the logs subdirectory creates a cross-site scripting opportunity. The flaw occurs during the rendering process of frontend/THEME/raw/index.html, where maliciously crafted filenames are not properly sanitized before being displayed to users. This represents a classic input validation and output encoding issue that allows attackers to inject malicious scripts into web pages viewed by legitimate users. The vulnerability specifically targets the logs directory functionality, which is a common administrative feature where system logs and user-generated content are stored and displayed. Attackers can exploit this by creating log files with malicious payloads in their filenames, which then get rendered without proper HTML escaping or sanitization. The impact extends to any user who views the affected logs page, potentially compromising their session cookies, browser state, or enabling further attacks. This vulnerability aligns with CWE-79 which describes improper neutralization of input during web page generation, and specifically relates to CWE-80 which addresses HTML injection in web applications. The attack vector follows the ATT&CK technique T1059.007 for command and control communication through web shells or XSS payloads, and T1566 for social engineering via malicious web content. The technical flaw stems from the lack of proper input validation and output encoding in the cPanel template rendering system, where user-provided data flows directly into HTML output without adequate sanitization. The operational impact includes potential session hijacking, data theft, and privilege escalation if the victim is an administrator with elevated permissions. This vulnerability can be exploited by any user with access to create or modify files in the logs directory, making it particularly dangerous in shared hosting environments. The remediation involves implementing proper input validation and output encoding mechanisms, ensuring all user-supplied content is escaped before rendering in HTML contexts. Additionally, implementing Content Security Policy headers and regular security audits of template rendering processes would significantly reduce the risk of similar vulnerabilities. The vulnerability demonstrates the critical importance of input sanitization in web applications and the potential consequences of inadequate security controls in administrative interfaces. Organizations should prioritize updating to patched versions of cPanel and implementing proper security measures to prevent similar issues in other web applications. This type of vulnerability highlights the need for comprehensive security testing including dynamic analysis and input validation reviews to identify potential XSS vectors in web applications.