CVE-2011-4768 in Plesk Small Business Panel
Summary
by MITRE
The Site Editor (aka SiteBuilder) feature in Parallels Plesk Small Business Panel 10.2.0 omits the Content-Type header s charset parameter for certain resources, which might allow remote attackers to have an unspecified impact by leveraging an interpretation conflict involving Wizard/Edit/Modules/Image and certain other files. NOTE: it is possible that only clients, not the Plesk product, could be affected by this issue.
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Analysis
by VulDB Data Team • 01/15/2018
The vulnerability identified as CVE-2011-4768 resides within the Site Editor functionality of Parallels Plesk Small Business Panel version 10.2.0, specifically affecting the Content-Type header implementation for certain web resources. This flaw represents a security oversight in how the system handles HTTP response headers, particularly the absence of charset parameter specification within the Content-Type header for various file types including Wizard/Edit/Modules/Image and related resources. The omission creates an interpretation conflict that can be exploited by remote attackers to potentially manipulate how browsers process and render web content, leading to unspecified security implications that could compromise the integrity of web applications served through the platform.
The technical nature of this vulnerability stems from improper HTTP header construction where the Content-Type header lacks the charset parameter that defines the character encoding of the resource being served. This deficiency allows for ambiguity in how web browsers interpret the content, potentially enabling attackers to exploit interpretation conflicts through malicious payload injection or content manipulation techniques. The vulnerability specifically affects resources that are typically handled through the SiteBuilder interface, which is designed to facilitate web content creation and management for users of the Plesk platform. According to CWE-1107, this represents a weakness in which a security-sensitive resource fails to properly specify its character encoding, creating potential for content injection attacks that leverage browser interpretation differences.
The operational impact of this vulnerability extends beyond simple content rendering issues, as it can potentially enable attackers to perform cross-site scripting attacks or manipulate how dynamic content is processed within the browser environment. When browsers encounter content without explicit charset specification, they may default to using their own interpretation methods or fallback encodings, which can create security gaps that malicious actors can exploit. The vulnerability's potential impact is particularly concerning given that it affects core web application functionality within Plesk's Site Editor, which is frequently used by administrators and end users to create and modify web content. This flaw essentially creates a vector for attackers to potentially inject malicious content that may be interpreted differently by various browsers, leading to unpredictable security consequences.
While the vulnerability description notes that it may only affect clients rather than the Plesk product itself, this distinction is critical for understanding the attack surface and potential exploitation pathways. The issue suggests that the security implications primarily manifest in how client browsers process the improperly formatted headers rather than through direct server-side vulnerabilities. However, this client-side impact still represents a significant security concern as it can enable various forms of content manipulation and potentially facilitate more sophisticated attacks. Organizations using Plesk Small Business Panel should consider this vulnerability as part of their broader security posture assessment, particularly in environments where multiple browser types are used or where content integrity is critical. The vulnerability aligns with ATT&CK technique T1566.001 which covers the use of malicious content through web applications, and represents a potential pathway for attackers to exploit browser interpretation inconsistencies.
Mitigation strategies should focus on ensuring proper header formatting for all web resources served through the Plesk platform, particularly those managed through the Site Editor functionality. System administrators should implement comprehensive testing of web content delivery to verify that all Content-Type headers properly specify charset parameters, and consider implementing automated monitoring for header consistency. The most effective approach involves applying the relevant security patches provided by Parallels, which would address the underlying implementation flaw in the Site Editor's header generation logic. Additionally, organizations should conduct regular security assessments of their Plesk installations to identify and remediate similar header-related vulnerabilities, as this type of issue often indicates broader security configuration gaps that could expose other components of the web application stack to similar risks.