CVE-2025-47167: Microsoft 365 Apps RCE Vulnerability

CVE-2025-47167 Overview

CVE-2025-47167 is a type confusion vulnerability in Microsoft Office that allows an unauthorized attacker to execute arbitrary code locally. This vulnerability stems from improper handling of resource types (CWE-843), where the application accesses a resource using an incompatible type, leading to memory corruption and potential code execution.

Type confusion vulnerabilities occur when code doesn't verify the type of an object being passed to it, and then blindly uses it without checking. This can allow attackers to manipulate program execution by supplying an object of an unexpected type, potentially leading to arbitrary code execution with the privileges of the current user.

Critical Impact

Successful exploitation enables unauthorized local code execution on affected Microsoft Office installations, potentially compromising document confidentiality, integrity, and system availability.

Affected Products

• Microsoft 365 Apps for Enterprise
• Microsoft Office 2016, 2019, and Android versions
• Microsoft Office Long Term Servicing Channel (LTSC) 2021 and 2024 for Windows and macOS

Discovery Timeline

• June 10, 2025 - CVE-2025-47167 published to NVD
• July 9, 2025 - Last updated in NVD database

Technical Details for CVE-2025-47167

Vulnerability Analysis

This type confusion vulnerability exists within Microsoft Office's resource handling mechanisms. When processing certain Office documents or objects, the application fails to properly validate the type of a resource before accessing it. This allows an attacker to craft a malicious document that presents an object as one type while it actually contains data structured as another type.

The vulnerability requires local access to exploit, meaning an attacker would need to convince a user to open a specially crafted document or achieve prior access to the target system. Once triggered, the type confusion can corrupt memory structures, potentially allowing the attacker to hijack program control flow and execute arbitrary code within the context of the Office application process.

The impact is significant as successful exploitation grants the attacker complete control over code execution with the user's privileges, enabling data theft, malware installation, or further system compromise.

Root Cause

The root cause is classified as CWE-843: Access of Resource Using Incompatible Type ('Type Confusion'). This occurs when the program allocates or initializes a resource such as a pointer, object, or variable using one type, but later accesses that resource using an incompatible type. In Microsoft Office's case, the vulnerable code path fails to implement proper type checking before operating on document objects or resources.

Type confusion bugs are particularly dangerous in complex applications like Microsoft Office because:

• Objects may be passed through multiple abstraction layers
• Dynamic typing or polymorphism can mask type mismatches
• Memory layout differences between types can lead to exploitable conditions

Attack Vector

The attack vector for CVE-2025-47167 is local, requiring either user interaction to open a malicious document or prior access to the target system. An attacker would typically:

1. Craft a malicious Office document containing objects designed to trigger the type confusion
2. Deliver the document to the victim via email, file sharing, or other means
3. Convince the victim to open the document with an affected Microsoft Office version
4. Upon opening, the type confusion is triggered during document parsing or object handling
5. The attacker gains code execution with the privileges of the user running Office

The vulnerability does not require elevated privileges to exploit, and no user interaction beyond opening the malicious document is needed for the attack to succeed.

Detection Methods for CVE-2025-47167

Indicators of Compromise

• Unusual Office application crashes or unexpected behavior when opening specific documents
• Office processes spawning unexpected child processes or making unusual system calls
• Presence of suspicious or unrecognized Office document files with unusual internal structures
• Memory access violations or exception handling events in Office application logs

Detection Strategies

• Deploy endpoint detection and response (EDR) solutions capable of monitoring Office application behavior for anomalous activity
• Implement application whitelisting to detect unauthorized code execution from Office processes
• Monitor for suspicious Office document attachments in email security gateways using advanced threat detection
• Enable Windows Defender Application Guard for Office to isolate document processing in enterprise environments

Monitoring Recommendations

• Configure security information and event management (SIEM) rules to alert on Office process anomalies
• Enable enhanced logging for Microsoft Office applications and Windows event logs
• Monitor network traffic for unusual outbound connections from Office applications that could indicate post-exploitation activity
• Review Office application telemetry for patterns indicating exploitation attempts

How to Mitigate CVE-2025-47167

Immediate Actions Required

• Apply the latest Microsoft security updates immediately for all affected Office products
• Verify update deployment across all endpoints using Microsoft Configuration Manager or similar tools
• Educate users about the risks of opening documents from untrusted sources
• Enable Protected View settings in Microsoft Office to open documents from the internet in read-only mode

Patch Information

Microsoft has released security updates to address CVE-2025-47167. Detailed patch information and update guidance are available in the Microsoft Security Update Guide for CVE-2025-47167. Organizations should apply the appropriate updates for their specific Office versions including Microsoft 365 Apps, Office 2016, Office 2019, and Office LTSC 2021/2024.

Workarounds

• Enable Protected View for all Office documents to prevent automatic execution of potentially malicious content
• Configure Office to block macros and active content from untrusted sources as an additional defense layer
• Use Microsoft Defender Application Guard for Office in enterprise environments to isolate document rendering
• Restrict Office file type associations to prevent automatic opening of documents from external sources

# PowerShell: Enable Protected View for files from the Internet
Set-ItemProperty -Path "HKCU:\Software\Microsoft\Office\16.0\Word\Security\ProtectedView" -Name "DisableInternetFilesInPV" -Value 0 -Type DWord
Set-ItemProperty -Path "HKCU:\Software\Microsoft\Office\16.0\Excel\Security\ProtectedView" -Name "DisableInternetFilesInPV" -Value 0 -Type DWord
Set-ItemProperty -Path "HKCU:\Software\Microsoft\Office\16.0\PowerPoint\Security\ProtectedView" -Name "DisableInternetFilesInPV" -Value 0 -Type DWord