CVE-2011-4776 in Plesk Panel
Summary
by MITRE
Multiple cross-site scripting (XSS) vulnerabilities in the Control Panel in Parallels Plesk Panel 10.4.4_build20111103.18 allow remote attackers to inject arbitrary web script or HTML via crafted input to a PHP script, as demonstrated by admin/update/settings/ and certain other files.
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Analysis
by VulDB Data Team • 01/29/2018
The vulnerability identified as CVE-2011-4776 represents a critical cross-site scripting flaw within the administrative interface of Parallels Plesk Panel version 10.4.4_build20111103.18. This issue affects the Control Panel component of the web hosting management platform, which serves as the primary interface for system administrators to manage server configurations, user accounts, and hosting services. The vulnerability specifically targets the admin/update/settings/ endpoint and other related PHP scripts that process user input without proper sanitization or validation mechanisms.
The technical flaw stems from insufficient input validation and output encoding practices within the affected PHP scripts. Attackers can exploit this weakness by crafting malicious payloads that contain executable JavaScript code or HTML elements, which are then processed and rendered within the administrative interface without appropriate sanitization. When authenticated administrators view pages containing the malicious input, the injected scripts execute in their browser context, potentially leading to session hijacking, privilege escalation, or data exfiltration. This vulnerability operates at the application layer and leverages the trust relationship between the legitimate administrator and the web application to compromise the system's security posture.
The operational impact of this vulnerability extends beyond simple script injection, as it provides attackers with a potential foothold for more sophisticated attacks within the hosting environment. An attacker who successfully exploits this vulnerability could gain access to sensitive administrative functions, modify server configurations, steal administrative credentials, or manipulate hosting services for malicious purposes. The attack surface is particularly concerning because it targets the control panel, which typically contains the most privileged access points within a hosting infrastructure. This vulnerability aligns with CWE-79, which categorizes cross-site scripting flaws as a common weakness in web applications, and represents a direct threat to the principle of least privilege and secure input handling.
Mitigation strategies for CVE-2011-4776 should prioritize immediate patching of the affected Parallels Plesk Panel version, as vendors typically release security updates to address such vulnerabilities. Organizations should also implement input validation at multiple layers, including server-side sanitization of all user-provided data before processing or storage. Network-based protections such as web application firewalls can provide additional defense-in-depth measures, though these should not replace proper code-level fixes. Security monitoring should focus on detecting anomalous administrative activities or unexpected changes to system configurations that might indicate exploitation attempts. The ATT&CK framework categorizes this vulnerability under T1059.007 for scripting and T1566.001 for spearphishing with social engineering, highlighting the need for both technical controls and user awareness training to prevent successful exploitation.