CVE-2022-30173
📋 TL;DR
CVE-2022-30173 is a remote code execution vulnerability in Microsoft Excel that allows attackers to execute arbitrary code on a victim's system by tricking them into opening a specially crafted Excel file. This affects users running vulnerable versions of Microsoft Excel on Windows systems. Successful exploitation requires user interaction but can lead to full system compromise.
💻 Affected Systems
- Microsoft Excel
📦 What is this software?
Excel by Microsoft
Excel by Microsoft
Excel by Microsoft
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise with attacker gaining the same privileges as the logged-in user, potentially leading to data theft, ransomware deployment, or persistent backdoor installation.
Likely Case
Malicious actor gains initial foothold on a workstation, then moves laterally within the network to steal sensitive data or deploy additional malware.
If Mitigated
Limited impact due to application sandboxing, least privilege accounts, and network segmentation preventing lateral movement.
🎯 Exploit Status
Requires user interaction to open malicious file. No public exploit code available as of last update.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Security updates released in June 2022 Patch Tuesday
Vendor Advisory: https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2022-30173
Restart Required: Yes
Instructions:
1. Open Excel and go to File > Account > Update Options > Update Now. 2. For enterprise deployments, deploy Microsoft security update KB5002252 (Excel 2016) or equivalent for your version. 3. Restart affected systems after patch installation.
🔧 Temporary Workarounds
Block Office file types from Internet
allConfigure email gateways and web proxies to block Excel files (.xls, .xlsx, .xlsm) from untrusted sources.
Enable Protected View
windowsEnsure Excel Protected View is enabled for files from the Internet to prevent automatic macro execution.
File > Options > Trust Center > Trust Center Settings > Protected View > Enable all options
🧯 If You Can't Patch
- Implement application whitelisting to prevent unauthorized Excel execution
- Use Microsoft Office Viewer or web-based Excel to open untrusted files instead of desktop Excel
🔍 How to Verify
Check if Vulnerable:
Check Excel version via File > Account > About Excel. Vulnerable if version is before June 2022 updates.Check Version:
powershell: Get-ItemProperty "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\*" | Where-Object {$_.DisplayName -like "*Excel*"} | Select-Object DisplayName, DisplayVersionVerify Fix Applied:
Verify Excel version shows build number after June 2022 updates (e.g., 16.0.14931.20128 for Office 2016).📡 Detection & Monitoring
Log Indicators:
- Excel crash logs with unusual memory addresses
- Windows Event Logs showing Excel spawning unexpected child processes
Network Indicators:
- Excel.exe making unexpected outbound connections after file open
- DNS requests to suspicious domains following Excel execution
SIEM Query:
source="windows_security" EventCode=4688 NewProcessName="*\cmd.exe" OR NewProcessName="*\powershell.exe" ParentProcessName="*\EXCEL.EXE"