CVE-2011-4726 in Plesk Panel
Summary
by MITRE
Multiple cross-site scripting (XSS) vulnerabilities in the Server Administration Panel in Parallels Plesk Panel 10.2.0_build1011110331.18 allow remote attackers to inject arbitrary web script or HTML via crafted input to a PHP script, as demonstrated by admin/health/ and certain other files.
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Analysis
by VulDB Data Team • 01/12/2018
The vulnerability identified as CVE-2011-4726 represents a critical cross-site scripting flaw within the Server Administration Panel of Parallels Plesk Panel version 10.2.0_build101110331.18. This security weakness resides in the administrative interface components, specifically affecting the admin/health/ directory and several other PHP scripts that handle user input. The flaw allows remote attackers to execute malicious web scripts or HTML code within the context of authenticated user sessions, potentially compromising the entire administrative environment. The vulnerability stems from insufficient input validation and output encoding mechanisms within the panel's PHP scripts, creating an attack surface where malicious payloads can be injected through carefully crafted user input fields or parameters.
The technical implementation of this vulnerability demonstrates a classic XSS flaw categorized under CWE-79, which specifically addresses improper neutralization of input during web page generation. Attackers can exploit this weakness by crafting malicious input that gets processed and displayed within the administrative panel without proper sanitization. The affected PHP scripts in the admin/health/ directory and related administrative components fail to properly encode or escape user-supplied data before rendering it in web responses. This allows attackers to inject JavaScript code or HTML content that executes in the browser context of legitimate administrators, potentially leading to session hijacking, privilege escalation, or complete system compromise. The vulnerability affects the server administration panel's ability to maintain secure output rendering, violating fundamental web application security principles.
The operational impact of CVE-2011-4726 extends beyond simple script injection, as it provides attackers with a potential foothold for more sophisticated attacks within the Plesk environment. When administrators interact with the compromised panel, the injected scripts execute in their browser context, potentially stealing session cookies, redirecting users to malicious sites, or modifying administrative settings. The vulnerability's location within the health monitoring section suggests that attackers could manipulate diagnostic information displays, potentially hiding malicious activity or creating false security alerts. This type of vulnerability directly aligns with ATT&CK technique T1566, which covers social engineering tactics through malicious web content, and T1071, which involves application layer protocols for command and control communications. The compromise of administrative interfaces can lead to complete system takeover, as administrators often possess elevated privileges and access to sensitive server configurations.
Organizations affected by this vulnerability should implement immediate mitigations including input validation and output encoding improvements across all administrative PHP scripts. The recommended remediation approach involves applying the vendor-provided security patches or updates that address the specific XSS vulnerabilities in the Plesk Panel administrative components. Security measures should include implementing Content Security Policy headers to prevent unauthorized script execution, enabling proper input sanitization routines, and conducting regular security assessments of administrative interfaces. Organizations should also consider implementing web application firewalls to detect and block malicious payloads targeting known XSS patterns. The vulnerability highlights the importance of maintaining up-to-date security patches and implementing proper security coding practices within administrative interfaces. Additionally, administrators should be trained to recognize potential XSS attack vectors and to verify the integrity of all administrative interface components through regular security audits.