CVE-2023-21695
📋 TL;DR
This vulnerability allows remote code execution on systems using Microsoft's Protected Extensible Authentication Protocol (PEAP) for network authentication. Attackers can exploit heap-based buffer overflow in PEAP server components to execute arbitrary code with SYSTEM privileges. Affects Windows systems configured with PEAP authentication, particularly in enterprise environments using WPA2-Enterprise or 802.1X networks.
💻 Affected Systems
- Windows Server
- Windows Client
📦 What is this software?
Windows 10 by Microsoft
Windows 10 1607 by Microsoft
Windows 10 1809 by Microsoft
Windows 10 20h2 by Microsoft
Windows 10 21h2 by Microsoft
Windows 10 22h2 by Microsoft
Windows 11 21h2 by Microsoft
Windows 11 22h2 by Microsoft
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise with SYSTEM privileges, enabling lateral movement across network, credential theft, and persistent backdoor installation.
Likely Case
Remote code execution leading to malware deployment, data exfiltration, or ransomware attacks on vulnerable authentication servers.
If Mitigated
Limited to denial of service if exploit fails or is blocked by network segmentation and endpoint protection.
🎯 Exploit Status
Exploitation requires network access to PEAP authentication endpoint. No authentication needed to trigger vulnerability.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: January 2023 security updates (KB5022282 for Windows 10, KB5022303 for Windows 11, etc.)
Vendor Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-21695
Restart Required: Yes
Instructions:
1. Apply January 2023 Windows security updates via Windows Update. 2. For enterprise: Deploy through WSUS or Microsoft Endpoint Configuration Manager. 3. Restart systems after patch installation.
🔧 Temporary Workarounds
Disable PEAP authentication
windowsTemporarily disable PEAP authentication until patches can be applied
netsh wlan set profileparameter name="ProfileName" authentication=WPA2PSK
Network segmentation
allIsolate PEAP authentication servers from untrusted networks
🧯 If You Can't Patch
- Implement strict network access controls to limit access to PEAP endpoints
- Deploy intrusion prevention systems with signatures for PEAP buffer overflow attempts
🔍 How to Verify
Check if Vulnerable:
Check if PEAP is configured in network authentication settings and verify Windows version is unpatched for January 2023 updates.Check Version:
systeminfo | findstr /B /C:"OS Name" /C:"OS Version"Verify Fix Applied:
Verify Windows Update shows January 2023 security updates installed and check system version with winver command.📡 Detection & Monitoring
Log Indicators:
- Windows Security logs showing authentication failures from PEAP
- Event ID 4625 with authentication package PEAP
- Unexpected process creation from network service account
Network Indicators:
- Malformed PEAP packets to authentication servers
- Unusual traffic patterns to PEAP ports (UDP 1812, 1813)
SIEM Query:
source="windows_security" event_id=4625 authentication_package="PEAP" | stats count by src_ip