CVE-2011-4756 in Plesk Small Business Panel
Summary
by MITRE
Parallels Plesk Small Business Panel 10.2.0 does not include the HTTPOnly flag in a Set-Cookie header for a cookie, which makes it easier for remote attackers to obtain potentially sensitive information via script access to this cookie, as demonstrated by cookies used by domains/sitebuilder_edit.php and certain other files.
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Analysis
by VulDB Data Team • 01/26/2018
The vulnerability described in CVE-2011-4756 represents a critical security flaw in Parallels Plesk Small Business Panel version 10.2.0 that directly impacts web application security through improper cookie handling. This issue stems from the absence of the HTTPOnly flag in Set-Cookie HTTP headers, a fundamental security measure that prevents client-side script access to sensitive cookies. The vulnerability specifically affects cookies utilized by the domains/sitebuilder_edit.php file and other related components within the Plesk control panel interface, creating a pathway for malicious actors to exploit the weakness through cross-site scripting attacks.
The technical nature of this vulnerability aligns with CWE-1004, which specifically addresses the lack of proper HTTPOnly flag implementation in cookie security. When cookies lack the HTTPOnly flag, they become accessible to client-side scripting languages such as javascript, which exposes them to potential theft through XSS attacks. The attack vector demonstrates how remote adversaries can leverage script-based access to retrieve sensitive session information that would otherwise remain protected from client-side manipulation. This weakness fundamentally undermines the security boundary between the web application and client-side execution environments, allowing attackers to bypass traditional server-side cookie protection mechanisms.
The operational impact of this vulnerability extends beyond simple information disclosure, creating a significant risk for Plesk administrators and their hosted domains. Attackers who successfully exploit this weakness can obtain session cookies that grant them unauthorized access to user accounts and administrative functions within the Plesk environment. This compromise can lead to complete system takeover, data exfiltration, and unauthorized modifications to hosted websites and email configurations. The vulnerability particularly affects small business users who may not have robust security monitoring in place, making the potential impact more severe for organizations relying on this specific version of the Plesk control panel.
Mitigation strategies for CVE-2011-4756 should prioritize immediate patching of the affected Plesk version to the latest available release that includes proper HTTPOnly flag implementation. Security administrators must also implement comprehensive monitoring for unauthorized access attempts and conduct regular security assessments of their web applications to identify similar cookie security flaws. The remediation process should include thorough code reviews to ensure all Set-Cookie headers properly include the HTTPOnly flag, as well as implementation of additional security measures such as secure flag enforcement and proper session management practices. Organizations should also consider implementing web application firewalls and content security policies to provide additional defense layers against exploitation attempts targeting this specific vulnerability pattern.
This vulnerability exemplifies the importance of adhering to established security standards and best practices in web application development, particularly in relation to the ATT&CK framework's T1566 technique for credential access through social engineering and T1213 for data from information repositories. The flaw demonstrates how seemingly minor configuration issues can create substantial security risks when they align with common attack patterns and exploitation methodologies. Organizations must maintain continuous vigilance regarding cookie security implementation and ensure that all web applications properly implement security headers including HTTPOnly, Secure, and SameSite flags to prevent similar vulnerabilities from being exploited in their environments.