CVE-2016-0011 in SharePoint Foundation
Summary
by MITRE
Microsoft SharePoint Server 2013 SP1 and SharePoint Foundation 2013 SP1 allow remote authenticated users to bypass intended Access Control Policy restrictions and conduct cross-site scripting (XSS) attacks by modifying a webpart, aka "Microsoft SharePoint Security Feature Bypass," a different vulnerability than CVE-2015-6117.
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Analysis
by VulDB Data Team • 06/21/2018
This vulnerability represents a critical security flaw in Microsoft SharePoint Server 2013 SP1 and SharePoint Foundation 2013 SP1 that enables authenticated attackers to circumvent access control mechanisms and execute cross-site scripting attacks through webpart manipulation. The issue stems from insufficient validation of webpart parameters during the rendering process, allowing malicious users to inject malicious code that can be executed in the context of other users' browsers. This vulnerability specifically affects the security feature enforcement mechanisms within SharePoint's webpart handling system, creating a pathway for privilege escalation and unauthorized access to sensitive information.
The technical implementation of this vulnerability involves exploiting the way SharePoint processes and validates webpart configurations when users modify webpart properties. When authenticated users manipulate webpart parameters, the system fails to properly sanitize or validate input data, creating opportunities for attackers to inject malicious scripts. This bypass occurs because SharePoint's access control policies do not adequately verify the integrity of webpart modifications, particularly when these modifications involve dynamic content rendering. The vulnerability is classified as a security feature bypass, where the intended protection mechanisms are circumvented through careful manipulation of webpart attributes and parameters.
The operational impact of this vulnerability is significant as it allows attackers with valid user accounts to escalate their privileges and execute malicious code across multiple user sessions. The cross-site scripting component enables attackers to steal session cookies, redirect users to malicious sites, or perform actions on behalf of other users within the SharePoint environment. This creates a persistent threat vector that can be exploited repeatedly, as long as attackers maintain valid authentication credentials. The vulnerability affects the integrity and confidentiality of SharePoint environments, potentially leading to data breaches, unauthorized access to sensitive documents, and complete compromise of the collaboration platform.
Mitigation strategies for this vulnerability should focus on implementing comprehensive input validation and output encoding mechanisms within SharePoint webpart handling components. Organizations should deploy the latest security patches provided by Microsoft and consider implementing additional security controls such as web application firewalls to monitor and filter suspicious webpart modifications. The vulnerability aligns with CWE-79 which addresses cross-site scripting flaws, and may be related to ATT&CK technique T1059.001 for command and scripting interpreter and T1566 for credential access through phishing or social engineering. Administrators should also implement strict access controls and monitor user activities for unusual webpart modification patterns, while ensuring that SharePoint environments are properly configured with appropriate security headers and content security policies to prevent exploitation of such vulnerabilities.