SharePoint ToolShell · One Request PreAuth RCE Chain

AI-suggested

European organizations should immediately conduct thorough inventories to identify all SharePoint deployments, including on-premises and cloud-hosted instances. Given the absence of official patches, organizations should implement compensating controls such as restricting external access to SharePoint servers via network segmentation and firewall rules, enforcing strict access controls and monitoring for anomalous requests indicative of exploitation attempts. Deploying Web Application Firewalls (WAFs) with custom rules to detect and block suspicious SharePoint traffic can provide an additional layer of defense. Organizations should also enable comprehensive logging and real-time alerting on SharePoint servers to detect potential exploitation attempts early. Regularly reviewing and applying security updates from Microsoft is critical once patches become available. Furthermore, conducting penetration testing and vulnerability assessments focused on SharePoint can help identify exploitable configurations or weaknesses. Employee awareness training on phishing and social engineering is also advised, as attackers may combine this vulnerability with other tactics to gain initial access.