Microsoft Patches Critical SharePoint Connector Vulnerabilities in Power Platform

In February 2025, Microsoft addressed a critical security vulnerability affecting the SharePoint connector within its Power Platform suite. This vulnerability, if exploited, could have allowed threat actors to harvest user credentials and perform unauthorized actions within the SharePoint API, potentially leading to significant data breaches and unauthorized access to sensitive information.

Understanding the Vulnerability

The core of the issue was identified as a Server-Side Request Forgery (SSRF) vulnerability. SSRF vulnerabilities occur when an attacker can manipulate a server into making unintended requests to internal or external systems. In this specific case, the vulnerability stemmed from the "custom value" functionality within the SharePoint connector, which permitted attackers to insert their own URLs as part of a flow. This manipulation could lead to unauthorized requests being sent on behalf of the impersonated user.

Potential Impact

If successfully exploited, this vulnerability could have manifested in several detrimental ways:

Credential Harvesting: Attackers could capture SharePoint JSON Web Tokens (JWT) access tokens, allowing them to impersonate users and access sensitive data.
Unauthorized Data Access: With the harvested tokens, malicious actors could send requests to the SharePoint API, retrieving or modifying data without proper authorization.
Expanded Attack Surface: The vulnerability extended beyond just the SharePoint connector. Services like Power Automate, Power Apps, Copilot Studio, and Copilot 365 were also at risk, broadening the potential impact across the entire Power Platform ecosystem.

Prerequisites for Exploitation

For an attacker to successfully exploit this vulnerability, certain conditions needed to be met:

The attacker required the Environment Maker role within the Power Platform.
Possession of the Basic User role was also necessary.

These prerequisites imply that an attacker would first need to gain access to a target organization and acquire these roles, either through legitimate means or via other malicious activities.

Microsoft's Response

Upon responsible disclosure of the vulnerability in September 2024, Microsoft promptly initiated an investigation. By December 13, 2024, the company released a patch to address the security flaw. The severity of the vulnerability was assessed as "Important," and users were strongly advised to apply the update to mitigate potential risks.

Best Practices for Users

To safeguard against such vulnerabilities, users and administrators are encouraged to adopt the following best practices:

Regular Updates: Ensure that all components of the Power Platform are kept up-to-date with the latest security patches.
Role Management: Regularly review and manage user roles within the Power Platform to ensure that only authorized individuals have elevated privileges.
Data Loss Prevention (DLP) Policies: Implement DLP policies to control which connectors can be used within the environment, thereby reducing the risk of unauthorized data access.
Monitoring and Alerts: Set up monitoring to detect unusual activities and configure alerts to notify administrators of potential security incidents.

Conclusion

Microsoft's swift action in addressing the SSRF vulnerability within the SharePoint connector underscores the importance of proactive security measures. By staying vigilant and adhering to best practices, organizations can significantly reduce the risk of exploitation and ensure the integrity of their data within the Power Platform ecosystem.