CVE-2016-10776 in cPanel
Summary
by MITRE
cPanel before 60.0.25 allows stored XSS during the homedir removal phase of WHM Account termination (SEC-174).
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Analysis
by VulDB Data Team • 07/21/2020
The vulnerability identified as CVE-2016-10776 represents a critical stored cross-site scripting flaw within cPanel software versions prior to 60.0.25. This security weakness specifically manifests during the homedir removal phase of WHM Account termination processes, creating a persistent threat vector that can affect multiple users simultaneously. The vulnerability falls under the category of stored XSS attacks where malicious payloads are injected into the system and subsequently executed whenever affected users access the compromised interface. This particular flaw demonstrates the dangerous potential of administrative tools to become attack vectors when proper input validation and output sanitization mechanisms are absent. The security implications extend beyond simple data theft as stored XSS can enable attackers to execute arbitrary JavaScript code within the context of authenticated users' browsers, potentially leading to complete account compromise and privilege escalation.
The technical implementation of this vulnerability stems from insufficient validation of user-supplied data during the account termination process within WHM's homedir removal functionality. When administrators or authorized users perform account termination operations, the system fails to properly sanitize or escape input parameters that are subsequently stored and later rendered in web interfaces. This allows attackers to inject malicious JavaScript payloads through the account termination workflow, which then executes whenever legitimate users access the affected administrative panels. The flaw operates at the application layer and specifically targets the web-based management interface of cPanel, making it particularly dangerous for environments where multiple administrators or users interact with the system. According to CWE standards, this vulnerability maps to CWE-79 which describes improper neutralization of input during web page generation, and more specifically to CWE-80 which addresses the improper neutralization of script in a web page. The attack vector follows the pattern described in MITRE ATT&CK framework under technique T1059.007 for command and scripting interpreter, where attackers leverage web-based interfaces to execute malicious code.
The operational impact of this vulnerability extends far beyond simple script injection, as it provides attackers with persistent access to compromised systems through the cPanel administrative interface. When successful, stored XSS can enable attackers to steal session cookies, modify user permissions, access sensitive account information, and potentially escalate privileges to full system control. The vulnerability affects all users who have access to the WHM account termination functionality, making it particularly dangerous in multi-user environments where administrative privileges are shared. Attackers can craft malicious payloads that execute automatically when legitimate users access the affected interface, creating a stealthy attack vector that can operate for extended periods without detection. The impact is amplified by the fact that cPanel serves as a critical management tool for web hosting environments, making successful exploitation potentially devastating for entire hosting providers and their customers. Organizations running vulnerable versions of cPanel face significant risk of data breaches, unauthorized access to customer accounts, and potential compromise of entire hosting infrastructure, as the vulnerability exists within the core administrative functionality of the software.
Mitigation strategies for CVE-2016-10776 require immediate patching of cPanel installations to version 60.0.25 or later, which contains the necessary security fixes to prevent the stored XSS vulnerability. Organizations should also implement additional defensive measures including regular security audits of administrative interfaces, enhanced input validation and output sanitization procedures, and monitoring for suspicious activity within the WHM account termination processes. Network segmentation and least privilege access controls should be enforced to limit exposure of administrative interfaces to only authorized personnel. Security teams should also consider implementing web application firewalls to detect and block suspicious script injection attempts, while maintaining comprehensive logging and monitoring of administrative activities. Regular security training for system administrators regarding the risks of stored XSS and proper input validation practices is essential. Organizations should also conduct vulnerability assessments to identify other potential stored XSS vulnerabilities within their cPanel installations and related web applications, as this type of flaw often indicates broader input validation weaknesses that may affect other components of the hosting infrastructure. The remediation process must include thorough testing to ensure that the patch does not introduce compatibility issues with existing hosting configurations while maintaining the security integrity of the administrative interfaces.