CVE-2016-10813 in cPanel
Summary
by MITRE
cPanel before 57.9999.54 allows self XSS during ftp account creation under addon domains (SEC-118).
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Analysis
by VulDB Data Team • 11/14/2023
The vulnerability identified as CVE-2016-10813 represents a critical self-cross-site scripting flaw within cPanel software versions prior to 57.9999.54. This security defect specifically manifests during the creation of FTP accounts under addon domains, creating a persistent vector for malicious exploitation. The vulnerability falls under the category of stored cross-site scripting attacks where malicious input is not properly sanitized before being rendered back to users. The flaw allows attackers to inject malicious scripts that execute in the context of the victim's browser when they interact with the affected cPanel interface. This particular vulnerability is classified under CWE-79 as a cross-site scripting weakness, where the application fails to properly validate and sanitize user-supplied input before incorporating it into dynamically generated web pages. The attack scenario involves an attacker creating an FTP account with malicious script content in the account details, which then gets stored and executed whenever legitimate users view the FTP account information within the cPanel interface. This creates a persistent threat that can affect any user who accesses the compromised FTP account details, making it particularly dangerous in shared hosting environments where multiple users interact with the same cPanel instance.
The technical implementation of this vulnerability stems from inadequate input validation and output encoding mechanisms within the cPanel FTP account creation module. When users create FTP accounts under addon domains, the system accepts user input without sufficient sanitization of special characters that could be interpreted as HTML or JavaScript code. The vulnerability specifically affects the rendering process of FTP account information within the cPanel administrative interface, where the system fails to properly escape or encode potentially malicious content. This flaw allows attackers to craft malicious payloads that can steal session cookies, perform unauthorized actions on behalf of users, or redirect victims to malicious websites. The vulnerability is particularly concerning because it operates as a self-XSS attack, meaning the malicious code is stored within the application itself rather than requiring external exploitation. The attacker does not need to trick users into clicking external links or performing specific actions beyond accessing the compromised FTP account information. The attack follows the typical ATT&CK technique T1059.001 for command and control through script injection, where the malicious code executes within the victim's browser context. This vulnerability enables attackers to establish persistent access to compromised accounts and potentially escalate privileges within the cPanel environment.
The operational impact of CVE-2016-10813 extends beyond simple script execution, as it provides attackers with significant privileges within the compromised cPanel environment. When exploited successfully, the vulnerability allows attackers to manipulate FTP account configurations, potentially gaining unauthorized access to user files and directories. The stored nature of the XSS payload means that any user who views the compromised FTP account information becomes a victim of the attack, creating a wide potential attack surface. This vulnerability can be leveraged to perform account takeover attacks, where attackers steal session information or credentials from legitimate users who interact with the compromised interface. The impact is particularly severe in hosting environments where multiple customers share the same cPanel instance, as a single compromised account can potentially affect the entire hosting environment. Additionally, the vulnerability can be used to establish backdoor access points within the hosting infrastructure, allowing attackers to maintain persistent access to the compromised systems. The vulnerability also poses risks to data integrity and confidentiality, as attackers can modify or exfiltrate sensitive information stored within the FTP accounts. The long-term implications include potential compromise of customer data, reputation damage to hosting providers, and possible regulatory compliance violations. Organizations using affected cPanel versions face significant risk of unauthorized access to customer resources and potential data breaches that could result in financial losses and legal consequences.
Mitigation of this vulnerability requires immediate patching of cPanel installations to versions 57.9999.54 or later, which contain the necessary security fixes to prevent the improper handling of user input during FTP account creation. System administrators should implement comprehensive input validation and output encoding mechanisms to prevent similar vulnerabilities from emerging in other parts of the application. The patch addresses the root cause by ensuring that all user-supplied input is properly sanitized and escaped before being rendered in the web interface. Organizations should also implement additional security controls such as web application firewalls to detect and block malicious input patterns, and conduct regular security assessments of their cPanel installations. Regular monitoring of the cPanel interface for suspicious activity and user behavior anomalies can help detect exploitation attempts. Security teams should also consider implementing privileged access controls and least-privilege principles to limit the potential damage from successful exploitation attempts. The mitigation strategy should include regular security training for administrators to recognize and respond to potential XSS attack vectors. Organizations should establish incident response procedures specifically addressing XSS vulnerabilities and maintain up-to-date vulnerability management processes. Additionally, implementing proper input sanitization libraries and ensuring all web application components follow secure coding practices can prevent similar vulnerabilities from occurring in other parts of the hosting infrastructure. The fix aligns with industry best practices for preventing XSS vulnerabilities as outlined in OWASP Top 10 and NIST cybersecurity guidelines, emphasizing the importance of proper input validation and output encoding in web application security.