CVE-2016-10781 in cPanel
Summary
by MITRE
cPanel before 60.0.25 allows self XSS in the UI_confirm API (SEC-180).
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Analysis
by VulDB Data Team • 07/21/2020
The vulnerability CVE-2016-10781 represents a self cross-site scripting flaw in cPanel versions prior to 60.0.25, specifically within the UI_confirm API component. This issue falls under the category of CWE-79 Cross-Site Scripting, where malicious input is not properly sanitized before being rendered in the user interface. The vulnerability manifests when the UI_confirm API processes user input without adequate validation or encoding, allowing attackers to inject malicious scripts that execute within the context of the victim's browser session.
The technical implementation of this vulnerability occurs in the API's handling of confirm dialog parameters where user-supplied data is directly incorporated into HTML output without proper sanitization. When cPanel renders confirmation dialogs for administrative operations, the API accepts input values that should be treated as untrusted and validated before being displayed to users. This creates an environment where an attacker can craft malicious payloads that, when processed by the UI_confirm API, execute in the victim's browser context with the privileges of the authenticated user.
The operational impact of this vulnerability is significant as it enables attackers to perform actions that would normally require legitimate administrative access. An attacker could potentially steal session cookies, modify user settings, or execute unauthorized administrative commands by leveraging the self-XSS vector. The vulnerability is particularly dangerous because it operates within the cPanel administrative interface, which typically has elevated privileges and access to sensitive system configurations. This could lead to complete system compromise if attackers can escalate privileges or gain access to additional administrative functions through the compromised session.
The mitigation strategy involves upgrading to cPanel version 60.0.25 or later, which includes proper input sanitization and output encoding for the UI_confirm API. Organizations should also implement comprehensive input validation measures, including the use of context-specific encoding for all user-supplied data before rendering in UI components. Security best practices recommend implementing Content Security Policy headers to limit script execution and employing regular security audits of API endpoints to identify similar vulnerabilities. This vulnerability aligns with ATT&CK technique T1059.001 Command and Scripting Interpreter for Web Shells and T1566 Phishing for Information, as it enables attackers to establish persistent access through malicious script injection within the trusted administrative interface.
The vulnerability demonstrates the critical importance of proper input validation in web applications, particularly in administrative interfaces where user input directly influences UI rendering. It underscores the need for defense-in-depth approaches that include both server-side validation and client-side security measures. Organizations should conduct regular penetration testing and vulnerability assessments of their administrative interfaces to identify similar injection vulnerabilities that could be exploited for privilege escalation or unauthorized access. The fix implemented in cPanel 60.0.25 likely involved implementing proper HTML entity encoding for all user-supplied parameters and establishing stricter validation rules for API input to prevent malicious script execution within the administrative context.