CVE-2018-8426 in SharePoint Enterprise Server
Summary
by MITRE
A cross-site-scripting (XSS) vulnerability exists when Microsoft SharePoint Server does not properly sanitize a specially crafted web request to an affected SharePoint server, aka "Microsoft Office SharePoint XSS Vulnerability." This affects Microsoft SharePoint Server, Microsoft SharePoint.
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Analysis
by VulDB Data Team • 05/08/2023
The vulnerability identified as CVE-2018-8426 represents a critical cross-site scripting flaw within Microsoft SharePoint Server implementations that has significant implications for enterprise security environments. This vulnerability stems from insufficient input validation and sanitization mechanisms within the SharePoint server's web request processing pipeline, creating an avenue for malicious actors to inject persistent or reflected scripts into web applications. The flaw specifically manifests when SharePoint Server fails to adequately sanitize user-supplied data within web requests, allowing attackers to craft malicious inputs that can execute arbitrary JavaScript code within the context of a victim's browser session.
The technical exploitation of this vulnerability occurs through the manipulation of web requests sent to affected SharePoint servers, where the application processes user input without proper validation or encoding mechanisms. This weakness enables attackers to inject malicious scripts that can be executed when other users view affected pages or interact with the SharePoint environment. The vulnerability affects Microsoft SharePoint Server versions that do not properly implement input sanitization routines, particularly in areas where user-generated content or parameters are processed and rendered back to users. The flaw operates at the application layer and can be leveraged to bypass standard security controls that would normally protect against such attacks, making it particularly dangerous in enterprise environments where SharePoint serves as a central collaboration platform.
The operational impact of CVE-2018-8426 extends beyond simple script execution, as successful exploitation can lead to complete session hijacking, data exfiltration, and privilege escalation within the SharePoint environment. Attackers can leverage this vulnerability to steal user credentials, access sensitive documents, manipulate SharePoint content, or establish persistent access to the affected systems. The vulnerability's classification aligns with CWE-79, which specifically addresses cross-site scripting flaws in web applications, and follows the ATT&CK technique T1566 for social engineering through malicious content delivery. Organizations utilizing SharePoint Server may experience significant security breaches as attackers exploit this weakness to gain unauthorized access to corporate collaboration platforms where sensitive business information is stored and shared.
Mitigation strategies for this vulnerability should prioritize immediate patch deployment from Microsoft, as the company released security updates specifically addressing this flaw in their monthly security bulletin cycle. Organizations should implement comprehensive input validation and output encoding mechanisms within their SharePoint environments, ensuring that all user-supplied data is properly sanitized before being processed or displayed. Network segmentation and web application firewalls can provide additional layers of protection by monitoring and filtering malicious requests before they reach the SharePoint servers. Security teams should conduct thorough vulnerability assessments to identify potentially affected SharePoint installations and implement monitoring solutions to detect suspicious activities that may indicate exploitation attempts. Regular security awareness training for SharePoint administrators and users can help prevent social engineering attacks that might leverage this vulnerability to deliver malicious payloads through compromised SharePoint sites or documents.