CVE-2019-1212
📋 TL;DR
A memory corruption vulnerability in Windows Server DHCP service allows remote unauthenticated attackers to send specially crafted packets that could crash the DHCP server service. This affects Windows Server systems running vulnerable DHCP server configurations. The vulnerability could lead to denial of service and potentially remote code execution.
💻 Affected Systems
- Windows Server
📦 What is this software?
Windows 10 by Microsoft
Windows 10 by Microsoft
Windows 10 by Microsoft
Windows 10 by Microsoft
Windows 10 by Microsoft
Windows 7 by Microsoft
Windows 8.1 by Microsoft
Windows Rt 8.1 by Microsoft
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, though the CVE description specifically mentions denial of service
Likely Case
DHCP server service crash causing denial of service for network clients requiring DHCP services
If Mitigated
Limited impact if DHCP server is isolated or has redundancy, but still poses availability risk
🎯 Exploit Status
Remote unauthenticated exploitation with specially crafted packets, though specific exploit details not publicly documented
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: August 2019 security updates for Windows Server
Vendor Advisory: https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-1212
Restart Required: Yes
Instructions:
1. Apply August 2019 Windows Server security updates from Microsoft Update
2. Restart the DHCP server service or reboot the server
3. Verify the update was successfully applied
🔧 Temporary Workarounds
Network Segmentation
windowsRestrict access to DHCP server ports (UDP 67/68) to trusted networks only
Use Windows Firewall: New-NetFirewallRule -DisplayName "Block DHCP External" -Direction Inbound -Protocol UDP -LocalPort 67,68 -Action Block -RemoteAddress NotInLocalSubnet
DHCP Redundancy
windowsImplement DHCP failover clustering to maintain service availability if one server is compromised
Configure DHCP failover: In DHCP console, right-click scope, select 'Configure Failover'
🧯 If You Can't Patch
- Implement strict network segmentation to limit DHCP server exposure
- Deploy intrusion detection/prevention systems to monitor for DHCP protocol anomalies
🔍 How to Verify
Check if Vulnerable:
Check Windows Update history for August 2019 security updates or run: systeminfo | findstr /C:"KB"Check Version:
wmic qfe get hotfixid | findstr KB4507453 KB4507460 KB4507458 (example KBs - check specific for your version)Verify Fix Applied:
Verify August 2019 security updates are installed and DHCP service is running normally📡 Detection & Monitoring
Log Indicators:
- DHCP service crashes in Event Viewer (Event ID 7031, 7034)
- Unusual DHCP packet patterns in DHCP server logs
Network Indicators:
- Malformed DHCP packets to port 67/UDP
- Sudden stop of DHCP lease renewals from server
SIEM Query:
source="windows" event_id=7031 OR event_id=7034 service="dhcpserver"