CVE-2018-16636 in Nucleus
Summary
by MITRE
Nucleus CMS 3.70 allows HTML Injection via the index.php body parameter.
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Analysis
by VulDB Data Team • 06/13/2023
The vulnerability CVE-2018-16636 represents a critical HTML injection flaw within Nucleus CMS version 3.70, specifically affecting the index.php script through the body parameter. This issue falls under the category of input validation and output encoding failures that enable attackers to inject malicious HTML content into web pages. The vulnerability demonstrates a classic lack of proper sanitization mechanisms when processing user-supplied data, creating an avenue for cross-site scripting attacks that can compromise user sessions and data integrity. The affected parameter in the index.php file serves as an entry point for malicious actors to manipulate the application's output rendering behavior.
The technical exploitation of this vulnerability occurs when the application fails to properly validate or escape HTML characters in the body parameter before incorporating user input into the page content. This allows attackers to inject arbitrary HTML tags, scripts, or other malicious content that gets executed in the context of other users' browsers. The flaw essentially bypasses the CMS's intended security controls, enabling attackers to manipulate the content delivery mechanism and potentially escalate privileges or steal sensitive information. The vulnerability is particularly concerning because it operates at the application layer, where user input directly influences the dynamic generation of web content.
From an operational impact perspective, this HTML injection vulnerability creates significant risks for Nucleus CMS users and administrators. Attackers can exploit this flaw to perform session hijacking, steal cookies, redirect users to malicious sites, or inject phishing content that appears legitimate to end users. The vulnerability affects the core functionality of the content management system, potentially compromising the integrity of all pages that utilize the affected parameter. Organizations using this CMS version face increased exposure to social engineering attacks and data breaches, as the injected HTML content can be designed to harvest user credentials or establish backdoor access points. The attack surface extends beyond individual page manipulation to potentially affect entire user bases if the vulnerability is leveraged in a widespread manner.
Security professionals should consider this vulnerability in the context of the CWE-79 weakness category, which specifically addresses cross-site scripting vulnerabilities resulting from insufficient input validation and output encoding. The ATT&CK framework categorizes this type of vulnerability under the T1059.001 technique for command and control communications, where injected HTML can serve as a vehicle for establishing persistent access. Mitigation strategies must include immediate implementation of proper input sanitization routines, deployment of web application firewalls, and comprehensive code review to identify similar patterns in other parameters. Organizations should also implement strict output encoding mechanisms that prevent HTML characters from being interpreted as executable content. The recommended remediation involves upgrading to a patched version of Nucleus CMS or implementing comprehensive input validation and sanitization measures that filter out potentially malicious HTML content before it reaches the application's output rendering components.