CVE-2020-1100 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 CVE ID is unique from CVE-2020-1099, CVE-2020-1101, CVE-2020-1106.
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Analysis
by VulDB Data Team • 02/28/2025
The vulnerability described in CVE-2020-1100 represents a critical cross-site scripting flaw within Microsoft SharePoint Server that allows attackers to inject malicious scripts into web requests processed by affected systems. This vulnerability specifically targets the server's failure to properly sanitize input data from web requests, creating an exploitable condition that can be leveraged by malicious actors to execute arbitrary code within the context of a user's browser session. The flaw exists in the SharePoint Server's request handling mechanism where user-supplied input is not adequately validated or escaped before being rendered in web pages, enabling attackers to craft malicious payloads that can persist and execute across user sessions.
The technical implementation of this XSS vulnerability stems from insufficient input validation and output encoding within SharePoint Server's web request processing pipeline. When a specially crafted web request is submitted to an affected SharePoint server, the system fails to properly sanitize the input parameters before incorporating them into dynamic web content. This weakness allows attackers to inject malicious script code that gets executed when other users view the affected pages. The vulnerability is classified as a persistent XSS attack vector because the malicious code can be stored on the server and executed whenever users access the compromised content, making it particularly dangerous in collaborative environments where multiple users interact with shared documents and web pages. This flaw aligns with CWE-79 which specifically addresses Cross-site Scripting vulnerabilities in web applications.
The operational impact of CVE-2020-1100 extends beyond simple script execution to encompass significant security risks including session hijacking, credential theft, and potential lateral movement within network environments. Attackers can leverage this vulnerability to steal user authentication tokens, access sensitive documents, and escalate privileges within the SharePoint environment. The vulnerability affects the confidentiality, integrity, and availability of SharePoint server resources, potentially allowing unauthorized access to corporate data repositories and collaboration platforms. Organizations using SharePoint Server for document management, team collaboration, and intranet portals face heightened risk of data breaches and unauthorized access attempts. The attack surface is particularly broad given that SharePoint servers often serve as central hubs for enterprise collaboration and information sharing, making successful exploitation potentially devastating for organizational security postures. This vulnerability maps to several ATT&CK techniques including T1059.007 for Scripting and T1566 for Phishing, demonstrating how the XSS flaw can serve as a launching point for more sophisticated attack chains.
Mitigation strategies for CVE-2020-1100 should encompass both immediate patch management and defensive configuration measures. Microsoft released security updates addressing this vulnerability through regular monthly patches, and organizations must prioritize applying these updates to affected SharePoint Server installations. Additionally, implementing proper input validation mechanisms, output encoding, and web application firewalls can provide defense-in-depth measures against exploitation attempts. Security teams should conduct thorough vulnerability assessments of SharePoint environments to identify potentially affected components and implement monitoring solutions to detect anomalous web request patterns. Network segmentation and privileged access controls can limit the potential damage from successful exploitation attempts. Organizations should also consider implementing content security policies and regular security awareness training for users to reduce the risk of successful social engineering attacks that might leverage this vulnerability. The remediation process should include comprehensive testing to ensure that security updates do not disrupt critical SharePoint functionality while maintaining robust protection against this specific XSS vulnerability.