CVE-2017-8745 in SharePoint Foundation
Summary
by MITRE
An elevation of privilege vulnerability exists in Microsoft SharePoint Foundation 2013 Service Pack 1 when it does not properly sanitize a specially crafted web request to an affected SharePoint server, aka "Microsoft SharePoint Cross Site Scripting Vulnerability".
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Analysis
by VulDB Data Team • 01/12/2021
The vulnerability identified as CVE-2017-8745 represents a critical elevation of privilege flaw within Microsoft SharePoint Foundation 2013 Service Pack 1, classified under CWE-79 as a Cross-Site Scripting (XSS) vulnerability. This weakness arises from the inadequate sanitization of web requests processed by the SharePoint server, creating a pathway for malicious actors to exploit the system's security controls. The vulnerability specifically targets the server-side request handling mechanism where user-supplied input fails to undergo proper validation and sanitization before being processed or rendered within the web application context.
The technical exploitation of this vulnerability occurs when an attacker crafts a malicious web request that includes specially formatted input designed to bypass SharePoint's security filters. This crafted input typically involves HTML or JavaScript code that gets executed in the context of other users' sessions, allowing the attacker to escalate their privileges beyond what would normally be permitted. The flaw exists in the server's input validation logic where it fails to properly sanitize user-provided data before incorporating it into web responses, creating an environment where malicious payloads can be injected and executed.
From an operational impact perspective, this vulnerability enables attackers to perform unauthorized actions within the SharePoint environment with elevated privileges. Successful exploitation could allow an attacker to access sensitive information, modify content, create or delete user accounts, and potentially gain access to underlying systems. The attack surface extends to all users who interact with the SharePoint server, particularly affecting administrators and users with elevated permissions. The vulnerability's impact is amplified by the fact that it operates at the application layer, where the attacker can leverage the compromised system to perform further reconnaissance and lateral movement within the network infrastructure.
Security professionals should implement multiple layers of defense to mitigate this vulnerability, including immediate deployment of Microsoft security patches and updates to address the XSS flaw in SharePoint Foundation 2013. Network segmentation and access controls should be reinforced to limit the potential impact of successful exploitation, while monitoring systems should be configured to detect anomalous web requests that may indicate attempted exploitation. The vulnerability aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter and T1548.002 for Abuse of Functionality, demonstrating how XSS vulnerabilities can be leveraged for privilege escalation and system compromise. Organizations should also conduct regular security assessments of their SharePoint environments and implement comprehensive input validation controls to prevent similar vulnerabilities from emerging in future deployments.