CVE-2017-8569 in SharePoint
Summary
by MITRE
Microsoft SharePoint Server allows an elevation of privilege vulnerability due to the way that it sanitizes a specially crafted web request to an affected SharePoint server, aka "SharePoint Server XSS Vulnerability".
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Analysis
by VulDB Data Team • 12/31/2020
The vulnerability identified as CVE-2017-8569 represents a critical elevation of privilege flaw within Microsoft SharePoint Server that stems from inadequate input sanitization mechanisms. This weakness specifically manifests when the affected server processes web requests containing maliciously crafted payloads, allowing unauthorized users to potentially escalate their privileges within the system. The vulnerability operates through cross-site scripting (XSS) exploitation techniques that leverage the server's insufficient validation of user-supplied data, creating opportunities for attackers to manipulate server behavior and gain higher-level access rights.
From a technical perspective, the flaw resides in SharePoint Server's handling of web requests where the sanitization process fails to properly validate or escape potentially dangerous input parameters. This inadequate sanitization creates a pathway for attackers to inject malicious code that can execute within the context of the SharePoint server, potentially leading to unauthorized access to sensitive data, modification of content, or even complete system compromise. The vulnerability is particularly concerning because it operates at the server-side processing level, meaning that successful exploitation can occur without requiring authentication or specific user interaction beyond sending the malicious request. The attack vector typically involves crafting specially formatted HTTP requests that exploit the XSS mechanism to bypass security controls and establish elevated privileges.
The operational impact of this vulnerability extends beyond simple privilege escalation, potentially enabling attackers to access confidential information, modify or delete data, and manipulate the SharePoint environment. Organizations utilizing affected SharePoint Server versions face significant risks including data breaches, unauthorized content modification, and potential lateral movement within their network infrastructure. The vulnerability's exploitation can lead to complete compromise of the SharePoint server, affecting not just the targeted application but potentially the broader enterprise environment that relies on SharePoint for collaboration and document management services. Security teams must consider the potential for this vulnerability to serve as a stepping stone for more extensive attacks, particularly in environments where SharePoint servers are integrated with other enterprise systems.
Mitigation strategies for CVE-2017-8569 should prioritize immediate implementation of Microsoft security patches and updates released to address the specific XSS sanitization flaw. Organizations should conduct comprehensive vulnerability assessments to identify all affected SharePoint Server instances and ensure proper patch management procedures are in place. Network segmentation and monitoring solutions should be deployed to detect anomalous traffic patterns that might indicate exploitation attempts. Additionally, implementing robust input validation mechanisms, web application firewalls, and regular security audits can help reduce the attack surface and prevent successful exploitation. The vulnerability aligns with CWE-79 Cross-site Scripting and follows ATT&CK technique T1059 Command and Scripting Interpreter, as attackers may leverage the compromised server to execute malicious commands and scripts. Organizations should also consider implementing principle of least privilege access controls and regular security training for administrators to minimize potential impact from such vulnerabilities.