CVE-2025-30384: Microsoft SharePoint Server RCE Vulnerability

CVE-2025-30384 Overview

CVE-2025-30384 is an insecure deserialization vulnerability affecting Microsoft SharePoint Server that allows an unauthorized attacker to execute code locally. The vulnerability stems from improper handling of untrusted data during deserialization operations within the SharePoint application framework. When successfully exploited, an attacker with low privileges can achieve high impact on confidentiality, integrity, and availability of the affected system.

Critical Impact

Local code execution through insecure deserialization could allow attackers to compromise SharePoint Server environments, potentially accessing sensitive corporate data and pivoting to other network resources.

Affected Products

• Microsoft SharePoint Server Subscription Edition
• Microsoft SharePoint Server 2019
• Microsoft SharePoint Server 2016 Enterprise Edition

Discovery Timeline

• May 13, 2025 - CVE-2025-30384 published to NVD
• May 19, 2025 - Last updated in NVD database

Technical Details for CVE-2025-30384

Vulnerability Analysis

This vulnerability is classified under CWE-502 (Deserialization of Untrusted Data), a well-documented weakness pattern where applications deserialize data from untrusted sources without proper validation. In the context of SharePoint Server, the deserialization process fails to adequately verify the integrity and safety of incoming serialized objects before reconstructing them in memory.

The attack requires local access and involves high complexity, meaning successful exploitation depends on specific conditions being met within the target environment. Despite requiring an authenticated session with low privileges, the potential impact is significant—attackers can achieve complete compromise of confidentiality, integrity, and availability on the vulnerable system.

Root Cause

The root cause lies in SharePoint Server's handling of serialized data streams without implementing adequate security controls. When the application processes serialized objects, it fails to enforce strict type checking or implement allowlist-based deserialization controls. This allows maliciously crafted serialized payloads to instantiate arbitrary objects, potentially leading to code execution when dangerous classes are available in the application's classpath or assembly context.

Attack Vector

The attack vector is local, requiring the attacker to have some level of access to the SharePoint environment. The exploitation scenario involves crafting a malicious serialized payload that, when processed by the vulnerable SharePoint component, triggers the instantiation of dangerous object types. These objects can then be leveraged to execute arbitrary code within the context of the SharePoint application process.

Successful exploitation typically involves:

1. Identifying a deserialization endpoint or function within SharePoint
2. Crafting a serialized payload containing gadget chains that lead to code execution
3. Delivering the payload through an accessible input mechanism
4. Triggering the deserialization process to execute the malicious payload

For detailed technical information about this vulnerability, refer to the Microsoft Security Response Center advisory.

Detection Methods for CVE-2025-30384

Indicators of Compromise

• Unusual process spawning from SharePoint application pools (e.g., w3wp.exe launching cmd.exe or powershell.exe)
• Unexpected file creation or modification in SharePoint directories
• Anomalous network connections originating from SharePoint server processes
• Event log entries indicating deserialization errors or exceptions

Detection Strategies

• Monitor Windows event logs for application errors related to serialization exceptions in SharePoint
• Implement endpoint detection rules for suspicious child process creation from IIS worker processes
• Deploy network monitoring to detect unusual outbound connections from SharePoint servers
• Review SharePoint ULS logs for patterns indicating exploitation attempts

Monitoring Recommendations

• Enable verbose logging for SharePoint ULS to capture detailed application behavior
• Configure Security Information and Event Management (SIEM) alerts for SharePoint-related security events
• Implement file integrity monitoring on SharePoint installation directories
• Monitor privileged operations and authentication events on SharePoint servers

How to Mitigate CVE-2025-30384

Immediate Actions Required

• Apply the latest security updates from Microsoft for all affected SharePoint Server versions
• Review and restrict local access to SharePoint servers to authorized personnel only
• Implement network segmentation to limit lateral movement from compromised SharePoint instances
• Conduct security assessments to identify potential exposure

Patch Information

Microsoft has released security updates to address this vulnerability. Administrators should consult the Microsoft Security Response Center advisory for CVE-2025-30384 to obtain the appropriate patches for their SharePoint Server version. Apply patches during scheduled maintenance windows and ensure proper backup procedures are followed before deployment.

Workarounds

• Implement strict access controls to limit which users can interact with SharePoint serialization endpoints
• Deploy Web Application Firewall (WAF) rules to inspect and filter potentially malicious serialized payloads
• Enable enhanced monitoring on SharePoint servers until patches can be applied
• Consider temporarily isolating SharePoint servers from untrusted network segments if immediate patching is not feasible

# Example: Review SharePoint application pool processes for anomalies
Get-Process -Name w3wp | Select-Object Id, ProcessName, StartTime, CPU | Format-Table -AutoSize

# Example: Check for recent SharePoint security events in Windows Event Log
Get-EventLog -LogName Application -Source "SharePoint*" -Newest 50 | Where-Object {$_.EntryType -eq "Error"}