CVE-2025-47163: SharePoint Enterprise Server RCE Flaw

CVE-2025-47163 Overview

CVE-2025-47163 is an insecure deserialization vulnerability affecting Microsoft Office SharePoint that allows an authorized attacker to execute arbitrary code over a network. This vulnerability stems from improper handling of serialized data within SharePoint, enabling authenticated users with low-level privileges to craft malicious payloads that are deserialized by the server, ultimately resulting in remote code execution.

Critical Impact

An authenticated attacker can exploit this deserialization flaw to execute arbitrary code on the SharePoint server, potentially compromising the entire SharePoint environment and any sensitive data stored within it.

Affected Products

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

Discovery Timeline

• June 10, 2025 - CVE-2025-47163 published to NVD
• July 9, 2025 - Last updated in NVD database

Technical Details for CVE-2025-47163

Vulnerability Analysis

This vulnerability is classified as CWE-502 (Deserialization of Untrusted Data), a well-known weakness that occurs when an application deserializes data from an untrusted source without adequate validation. In the context of Microsoft SharePoint, the vulnerability allows authenticated attackers to submit specially crafted serialized objects that, when deserialized by the server, execute arbitrary code with the privileges of the SharePoint application pool identity.

The exploitation requires only low-level authentication (typically any SharePoint user), and the attack can be performed over the network without any user interaction. This makes the vulnerability particularly dangerous in enterprise environments where SharePoint is widely accessible to many users.

Root Cause

The root cause lies in SharePoint's deserialization logic, which does not properly validate or sanitize incoming serialized data before processing. When .NET deserialization is performed on attacker-controlled input, gadget chains within the application's assemblies can be leveraged to achieve code execution. This is a common pattern in .NET deserialization attacks where existing classes (gadgets) are chained together to perform malicious actions during the deserialization process.

Attack Vector

The attack is network-based and requires an authenticated user with basic SharePoint permissions. The attacker crafts a malicious serialized payload containing a gadget chain that, when deserialized by SharePoint, triggers arbitrary code execution. This can be delivered through various SharePoint endpoints that accept serialized data, such as web parts, workflow operations, or API calls.

Since this is a network-accessible vulnerability requiring only low privileges, it presents significant risk in enterprise environments. No user interaction is required beyond the attacker's own actions, and the impact affects confidentiality, integrity, and availability of the SharePoint server.

Detection Methods for CVE-2025-47163

Indicators of Compromise

• Unusual serialized payloads in SharePoint HTTP requests, particularly those containing known .NET gadget chain patterns
• Unexpected process spawning from the SharePoint application pool (w3wp.exe)
• Anomalous outbound network connections from SharePoint servers
• Error logs indicating deserialization exceptions or type resolution failures

Detection Strategies

• Monitor IIS logs for unusual POST requests to SharePoint endpoints with large or obfuscated payloads
• Implement network traffic analysis to detect patterns consistent with deserialization exploitation tools
• Deploy endpoint detection and response (EDR) solutions to identify suspicious child processes spawned from SharePoint worker processes
• Review Windows Event logs for .NET serialization-related errors and security events

Monitoring Recommendations

• Enable detailed logging for SharePoint and IIS to capture request payloads and response codes
• Configure SIEM rules to alert on deserialization attack patterns and known gadget chain signatures
• Monitor SharePoint server resource utilization for anomalies that could indicate exploitation attempts
• Implement file integrity monitoring on SharePoint directories to detect unauthorized modifications

How to Mitigate CVE-2025-47163

Immediate Actions Required

• Apply the security patches provided by Microsoft for SharePoint Enterprise Server 2016, SharePoint Server 2019, and SharePoint Server Subscription Edition immediately
• Review SharePoint user permissions and restrict access to only necessary users pending patch deployment
• Monitor SharePoint servers for signs of exploitation using the detection methods outlined above
• Consider temporarily restricting network access to SharePoint servers from untrusted networks

Patch Information

Microsoft has released security updates to address this vulnerability. Refer to the Microsoft Security Response Center Advisory for detailed patch information and download links specific to your SharePoint version. Organizations should prioritize patching given the network-accessible nature of this vulnerability and the potential for remote code execution.

Workarounds

• If immediate patching is not possible, implement web application firewall (WAF) rules to block known serialization exploit patterns
• Restrict SharePoint access to trusted networks and VPN connections only
• Implement strict network segmentation to limit lateral movement in case of compromise
• Review and minimize the number of authenticated users with access to SharePoint services

Organizations should treat this vulnerability with urgency given the combination of network accessibility, low privilege requirements, and code execution impact. SentinelOne customers benefit from behavioral detection capabilities that can identify suspicious process behavior and code execution patterns associated with deserialization attacks.