CVE-2025-27745
📋 TL;DR
CVE-2025-27745 is a use-after-free vulnerability in Microsoft Office that allows local attackers to execute arbitrary code on affected systems. This affects users who open malicious Office documents. The vulnerability requires user interaction but can lead to full system compromise.
💻 Affected Systems
- Microsoft Office
- Microsoft 365 Apps
📦 What is this software?
365 Apps by Microsoft
Office by Microsoft
Office by Microsoft
Office Long Term Servicing Channel by Microsoft
View all CVEs affecting Office Long Term Servicing Channel →
Office Long Term Servicing Channel by Microsoft
View all CVEs affecting Office Long Term Servicing Channel →
⚠️ Risk & Real-World Impact
Worst Case
Complete system takeover with administrative privileges, data theft, ransomware deployment, and lateral movement across the network.
Likely Case
Local privilege escalation leading to data exfiltration, persistence establishment, and credential harvesting from the compromised system.
If Mitigated
Limited impact with proper application sandboxing, restricted user privileges, and security software that blocks malicious document execution.
🎯 Exploit Status
Requires user interaction (opening malicious document); exploitation likely involves crafted Office files.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Microsoft Update for latest Office security updates
Vendor Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-27745
Restart Required: Yes
Instructions:
1. Open any Office application. 2. Go to File > Account > Update Options > Update Now. 3. Alternatively, use Windows Update for Office updates. 4. Restart Office applications after update.
🔧 Temporary Workarounds
Disable Office macro execution
windowsPrevents execution of potentially malicious macros in Office documents
Set Group Policy: Computer Configuration > Administrative Templates > Microsoft Office 2016 > Security Settings > Trust Center > Disable all macros without notification
Enable Protected View
windowsOpens documents from untrusted sources in read-only mode
Set Group Policy: Computer Configuration > Administrative Templates > Microsoft Office 2016 > Security Settings > Trust Center > Protected View
🧯 If You Can't Patch
- Implement application whitelisting to block unauthorized Office document execution
- Deploy endpoint detection and response (EDR) to monitor for suspicious Office process behavior
🔍 How to Verify
Check if Vulnerable:
Check Office version against Microsoft's security update guidance; vulnerable if running unpatched versionsCheck Version:
In Word/Excel: File > Account > About [Application] shows version numberVerify Fix Applied:
Verify Office version matches patched version in Microsoft advisory; ensure Windows Update shows no pending Office updates📡 Detection & Monitoring
Log Indicators:
- Unusual Office process spawning child processes
- Office crashes with memory access violations
- Suspicious document opens from untrusted sources
Network Indicators:
- Office processes making unexpected network connections
- Data exfiltration patterns following document opens
SIEM Query:
Office process execution followed by suspicious child process creation or network activity