CVE-2017-8629 in SharePoint Server
Summary
by MITRE
Microsoft SharePoint Server 2013 Service Pack 1 allows an elevation of privilege vulnerability when it fails to properly sanitize a specially crafted web request to an affected SharePoint server, aka "Microsoft SharePoint XSS Vulnerability".
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Analysis
by VulDB Data Team • 01/11/2021
The vulnerability identified as CVE-2017-8629 represents a critical elevation of privilege flaw within Microsoft SharePoint Server 2013 Service Pack 1 that stems from inadequate input validation mechanisms. This weakness enables attackers to exploit cross-site scripting vulnerabilities by crafting malicious web requests that bypass the server's sanitization protocols. The vulnerability specifically affects SharePoint's handling of user-supplied data within web requests, creating a pathway for unauthorized privilege escalation that could allow malicious actors to gain higher-level access rights than initially permitted. The flaw exists in the server's request processing logic where it fails to adequately validate and sanitize input parameters before processing them, leaving the system vulnerable to malicious input injection.
The technical implementation of this vulnerability operates through the exploitation of SharePoint's web request handling mechanisms where untrusted data enters the system through web forms, URL parameters, or other user-facing interfaces. When the server processes these requests without proper sanitization, it allows malicious scripts to be executed within the context of the victim's browser session. This creates a persistent threat vector that can be leveraged for session hijacking, data exfiltration, or privilege escalation attacks. The vulnerability is classified as a cross-site scripting weakness that enables attackers to manipulate the application's behavior and potentially escalate their privileges to administrative levels, depending on the specific implementation details of the SharePoint configuration and user permissions.
The operational impact of this vulnerability extends beyond simple XSS exploitation to encompass significant security implications for organizations relying on SharePoint Server 2013. Attackers can leverage this weakness to establish persistent access to sensitive corporate data, manipulate document libraries, and potentially gain administrative control over the SharePoint environment. The vulnerability's exploitation can result in data breaches, unauthorized access to confidential information, and disruption of business operations. Organizations may face regulatory compliance issues and potential legal consequences due to the exposure of sensitive data through this privilege escalation vector. The attack surface is particularly concerning in enterprise environments where SharePoint servers often host critical business applications and sensitive corporate information.
Mitigation strategies for CVE-2017-8629 should prioritize immediate implementation of Microsoft security patches and updates to address the underlying sanitization flaws. Organizations must also implement robust input validation mechanisms and web application firewalls to monitor and filter malicious requests before they reach the SharePoint servers. Network segmentation and least-privilege access controls should be enforced to limit the potential impact of successful exploitation attempts. Security monitoring systems should be configured to detect anomalous web request patterns that may indicate exploitation attempts. Regular security assessments and penetration testing should be conducted to identify and remediate similar vulnerabilities within the SharePoint environment and related applications. The vulnerability aligns with CWE-79 which specifically addresses cross-site scripting flaws, and may be mapped to ATT&CK technique T1059.007 for script execution through web applications, emphasizing the need for comprehensive security controls that address both the immediate vulnerability and broader application security posture.