Microsoft SharePoint's CVE-2025-30382: Unpacking the Deserialization RCE Risk
Introduction
Microsoft SharePoint Server, a cornerstone of enterprise collaboration, faces another critical security challenge with CVE-2025-30382. This deserialization vulnerability, rated at a CVSS score of 7.8, enables remote attackers to execute arbitrary code, potentially allowing full system compromise and lateral network movement.
Affected Systems and Versions
- Microsoft SharePoint Server Subscription Edition (specific vulnerable versions not explicitly listed; refer to Microsoft advisory KB5002705 for exact details)
Technical Information
CVE-2025-30382 arises from unsafe deserialization of untrusted data within SharePoint's metadata processing workflows. Specifically, the vulnerability exploits the Microsoft.SharePoint.Client.ServerRuntime namespace, where untrusted data is deserialized without proper validation. Attackers leverage .NET's BinaryFormatter to inject malicious objects into memory, enabling arbitrary code execution.
Attack Vectors and Exploitation Methods
- Remote Exploitation: Attackers can exploit this vulnerability by sending specially crafted HTTP requests to vulnerable SharePoint endpoints.
- Phishing and User Interaction: Users with elevated permissions might be tricked into uploading malicious payloads, triggering the vulnerability.
Patch Information
Organizations must apply Microsoft's security update KB5002705 immediately. The update addresses the vulnerability by enhancing validation mechanisms during deserialization processes.
Alternative Mitigations
- Restrict inbound network access to SharePoint servers.
- Disable unnecessary SharePoint services.
- Implement strict schema validation for XML/XSLT inputs.
Detection Methods
- Monitor HTTP logs for unusual POST requests to SharePoint endpoints, particularly requests containing serialized payloads.
- Deploy SIEM rules to detect anomalous activity related to deserialization processes.
Indicators of Compromise
- Suspicious
.aspxwebshell files appearing in SharePoint's_catalogs/masterpage/directory. - Unusual HTTP requests with specific User-Agent strings such as
Mozilla/4.0 (compatible; MSIE 6.0; MS Web Services Client Protocol).
Vendor Security History
Microsoft has previously faced similar deserialization vulnerabilities in SharePoint, notably CVE-2024-38094, which was actively exploited by ransomware groups. The recurring nature of these vulnerabilities highlights a need for improved secure coding practices and rigorous code audits.
