CVE-2011-4755 in Plesk Small Business Panel
Summary
by MITRE
Parallels Plesk Small Business Panel 10.2.0 does not properly validate string data that is intended for storage in an XML document, which allows remote attackers to cause a denial of service (parsing error) or possibly have unspecified other impact via a crafted cookie, as demonstrated by cookies to client@1/domain@1/hosting/file-manager/ and certain other files.
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Analysis
by VulDB Data Team • 01/29/2018
The vulnerability identified as CVE-2011-4755 affects Parallels Plesk Small Business Panel version 10.2.0, representing a critical security flaw in the web application's input validation mechanisms. This issue stems from insufficient sanitization of string data that is destined for XML document storage within the application's backend processes. The flaw specifically manifests when the system processes user-supplied data through cookies, which are then parsed and stored in XML format without adequate validation checks. The vulnerability exists in the application's handling of cookies sent to specific paths including client1/domain1/hosting/file-manager/ and related endpoints, making it exploitable through remote attack vectors without requiring authentication.
The technical nature of this vulnerability aligns with CWE-20, which describes improper input validation as a fundamental weakness in software applications. When crafted malicious cookies are submitted to the vulnerable endpoints, the application fails to properly sanitize the input data before incorporating it into XML structures. This parsing error creates a condition where the XML parser encounters malformed or unexpected data, leading to potential application crashes or denial of service conditions. The vulnerability's impact extends beyond simple denial of service, as the description suggests unspecified other impacts that could potentially include information disclosure or arbitrary code execution depending on the application's response to the malformed XML data.
From an operational perspective, this vulnerability presents significant risk to organizations relying on Plesk for web hosting management, as remote attackers can exploit it without authentication to disrupt service availability. The attack surface includes any user of the affected Plesk panel who accesses the vulnerable file manager endpoints, making it particularly dangerous in multi-tenant hosting environments where malicious users could potentially disrupt services for other customers. The vulnerability's exploitation requires minimal effort, as attackers only need to craft specific cookie values that will trigger the XML parsing failure when processed by the application's backend. This makes it an attractive target for automated attacks and could be leveraged as part of broader exploitation campaigns targeting web hosting infrastructure.
The security implications of this vulnerability extend to several ATT&CK techniques including T1210, which covers exploitation of remote services, and T1499, which covers endpoint disruption through resource consumption or service availability manipulation. Organizations should implement immediate mitigations including applying the vendor-provided patches, implementing web application firewalls to filter suspicious cookie content, and monitoring for unusual patterns in file manager access attempts. Additionally, network segmentation and access controls should be reviewed to limit exposure of the vulnerable endpoints to untrusted networks. The vulnerability demonstrates the importance of proper input validation and XML parsing security practices, highlighting the need for comprehensive security testing of all data processing pathways in web applications. Organizations should also consider implementing automated vulnerability scanning processes that can detect similar input validation flaws across their application portfolios to prevent exploitation of related vulnerabilities.