CVE-2011-4856 in Plesk Panel
Summary
by MITRE
The Control Panel in Parallels Plesk Panel 10.4.4_build20111103.18 sends incorrect Content-Type headers for certain resources, which might allow remote attackers to have an unspecified impact by leveraging an interpretation conflict involving admin/health/parameters 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 • 01/10/2018
The vulnerability identified as CVE-2011-4856 resides within the Parallels Plesk Panel 10.4.4_build20111103.18 control panel implementation where improper Content-Type header handling creates a potential security risk. This flaw specifically affects the admin/health/parameters endpoint and related files within the web application framework. The issue stems from the application's failure to correctly specify MIME types for certain resource files, creating an environment where remote attackers can potentially exploit interpretation conflicts between the server's response headers and client-side processing mechanisms.
The technical exploitation of this vulnerability occurs through a content-type interpretation conflict that can lead to various security implications. When the control panel serves specific administrative resources with incorrect Content-Type headers, it creates opportunities for attackers to manipulate how browsers or other HTTP clients interpret the received data. This misconfiguration can enable attackers to potentially execute malicious code, bypass security restrictions, or perform unauthorized actions within the administrative interface. The vulnerability demonstrates a classic case of improper input validation and output encoding that falls under CWE-74, which addresses improper neutralization of special elements used in data queries.
From an operational perspective, this vulnerability poses significant risks to system administrators and organizations relying on Plesk Panel for hosting management. The impact extends beyond simple data integrity concerns as it could potentially allow attackers to gain unauthorized access to administrative functions, modify system configurations, or compromise the entire hosting environment. The fact that only clients, not the Plesk product itself, may be affected suggests that the primary risk lies in how the application's responses are interpreted by client-side components rather than direct server compromise. This aligns with ATT&CK technique T1190, which involves exploiting vulnerabilities in client-side applications to gain unauthorized access or execute malicious code.
Organizations should implement immediate mitigations including updating to patched versions of Plesk Panel, implementing proper Content-Type header validation, and conducting thorough security assessments of their hosting environments. Network monitoring should be enhanced to detect anomalous Content-Type header behaviors, and administrators should review access controls to limit exposure to potential attackers. The vulnerability serves as a reminder of the critical importance of proper HTTP header management in web applications and the potential for seemingly minor configuration issues to create significant security risks. Organizations using legacy Plesk installations should prioritize upgrading to supported versions that address this and related vulnerabilities, as the affected build version represents an outdated security posture that leaves systems vulnerable to exploitation.