CVE-2016-10783 in cPanel
Summary
by MITRE
cPanel before 60.0.25 allows self stored XSS in SSL_listkeys (SEC-182).
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Analysis
by VulDB Data Team • 07/21/2020
The vulnerability identified as CVE-2016-10783 represents a critical cross-site scripting flaw within cPanel versions prior to 60.0.25, specifically affecting the SSL_listkeys functionality. This issue falls under the category of stored cross-site scripting attacks where malicious input is permanently stored on the server and subsequently executed when users access the affected page. The vulnerability was categorized as SEC-182 by cPanel's security team, indicating its severity and the need for immediate remediation. The flaw exists within the SSL certificate management interface, where user-supplied data is not properly sanitized before being rendered back to users, creating an attack vector that can be exploited by unauthorized individuals to inject malicious scripts into the web application's response.
The technical implementation of this vulnerability stems from inadequate input validation and output sanitization within the SSL_listkeys function. When administrators or users interact with the SSL certificate management section of cPanel, the application fails to properly escape or filter user-provided data before displaying it in the web interface. This allows attackers to submit malicious payloads through the SSL certificate listing functionality, which are then stored in the application's database or session storage. When other users access the same SSL certificate listing page, their browsers execute the injected scripts within the context of the vulnerable application, potentially leading to session hijacking, privilege escalation, or data exfiltration. The vulnerability specifically affects the SSL certificate management interface, where administrators might enter certificate names, serial numbers, or other metadata that gets displayed in the user interface without proper security measures.
The operational impact of CVE-2016-10783 extends beyond simple script execution, as it provides attackers with a persistent foothold within cPanel environments that could be leveraged for broader compromise. Since cPanel serves as a critical control interface for web hosting environments, successful exploitation could allow attackers to manipulate SSL certificates, potentially enabling man-in-the-middle attacks or impersonation of legitimate services. The stored nature of this vulnerability means that the malicious scripts remain active until the application is patched or the affected data is manually removed, creating a long-term security risk for organizations using vulnerable cPanel versions. Attackers could exploit this vulnerability to steal administrative credentials, modify SSL configurations, or redirect users to malicious websites, all while operating within the legitimate application context, making detection more difficult. This vulnerability directly relates to CWE-79 which defines cross-site scripting as the improper handling of untrusted data in web applications, and aligns with ATT&CK technique T1059.007 for scripting, where adversaries leverage web application vulnerabilities to execute malicious code.
Organizations affected by CVE-2016-10783 should prioritize immediate patching of their cPanel installations to version 60.0.25 or later, as this represents the first fixed release that addresses the stored XSS vulnerability in the SSL_listkeys functionality. The remediation process should include comprehensive testing of the patched environment to ensure that all SSL certificate management features function correctly without reintroducing the vulnerability. System administrators should also conduct thorough audits of their cPanel installations to identify any potential exploitation attempts that may have occurred prior to patching, including monitoring for unusual activity in SSL certificate management logs. Additionally, implementing proper input validation and output encoding measures at the application level can provide defense-in-depth protection against similar vulnerabilities, particularly in areas where user-supplied data is displayed within web interfaces. Organizations should also consider implementing web application firewalls and monitoring solutions that can detect and prevent exploitation attempts targeting known XSS vulnerabilities, while maintaining regular security assessments to identify and remediate similar issues within their hosting infrastructure.