CVE-2025-30375
📋 TL;DR
A type confusion vulnerability in Microsoft Office Excel allows attackers to execute arbitrary code on vulnerable systems by tricking users into opening malicious Excel files. This affects all users running unpatched versions of Microsoft Excel. The vulnerability requires user interaction but can lead to full system compromise.
💻 Affected Systems
- Microsoft Excel
📦 What is this software?
365 Apps by Microsoft
Excel 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 →
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 attacker gaining full control of the victim's computer, data theft, ransomware deployment, and lateral movement within the network.
Likely Case
Malware installation leading to data exfiltration, credential theft, or system disruption through malicious Excel documents.
If Mitigated
Limited impact with proper email filtering, user training, and application sandboxing preventing successful exploitation.
🎯 Exploit Status
Requires social engineering to deliver malicious file. Type confusion vulnerabilities often lead to reliable exploitation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Microsoft Security Update Guide for specific version
Vendor Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-30375
Restart Required: Yes
Instructions:
1. Open any Office application
2. Go to File > Account > Update Options > Update Now
3. For enterprise: Deploy through Microsoft Endpoint Configuration Manager or WSUS
4. Restart affected systems after patch deployment
🔧 Temporary Workarounds
Block Excel file execution via Group Policy
windowsPrevent Excel from opening files from untrusted sources
gpedit.msc > User Configuration > Administrative Templates > Microsoft Excel > Excel Options > Security > Trust Center > File Block Settings
Enable Protected View
windowsForce all Excel files from internet to open in Protected View
Excel Options > Trust Center > Trust Center Settings > Protected View > Enable all Protected View options
🧯 If You Can't Patch
- Implement application whitelisting to block unauthorized Excel execution
- Deploy email filtering to block suspicious Excel attachments
- Use Microsoft Defender Application Guard for Office
- Disable Excel macros and ActiveX controls
🔍 How to Verify
Check if Vulnerable:
Check Excel version against patched versions in Microsoft Security Update GuideCheck Version:
In Excel: File > Account > About ExcelVerify Fix Applied:
Verify Excel version matches or exceeds patched version in Microsoft advisory📡 Detection & Monitoring
Log Indicators:
- Excel crash logs with memory access violations
- Windows Event Logs showing Excel spawning unusual child processes
- Antivirus alerts for malicious Office documents
Network Indicators:
- Outbound connections from Excel process to suspicious IPs
- DNS requests for command and control domains from Office processes
SIEM Query:
source="*windows*" AND (process_name="EXCEL.EXE" AND (event_id=1000 OR event_id=1001)) OR (parent_process="EXCEL.EXE" AND process_name!="explorer.exe")