CVE-2024-26212
📋 TL;DR
This vulnerability in the DHCP Server Service allows an attacker to send specially crafted packets to cause a denial of service (DoS) condition, potentially crashing the service. It affects Windows Server systems running the DHCP server role. The vulnerability requires network access to the DHCP server port.
💻 Affected Systems
- Windows Server
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete unavailability of DHCP services, preventing new clients from obtaining IP addresses and existing clients from renewing leases, leading to widespread network connectivity issues.
Likely Case
DHCP service crashes requiring manual restart, causing temporary disruption to IP address assignment for new devices or lease renewals.
If Mitigated
Minimal impact with service restart capability and monitoring in place; potential brief service interruption during attack.
🎯 Exploit Status
Exploitation requires network access to DHCP server port (UDP 67). No authentication required.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Microsoft Security Update for specific KB number
Vendor Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2024-26212
Restart Required: Yes
Instructions:
1. Apply the latest Windows Server security update from Microsoft
2. Restart the DHCP server service or reboot the server
3. Verify the patch is applied using Windows Update history
🔧 Temporary Workarounds
Restrict Network Access
windowsLimit access to DHCP server port (UDP 67) to only trusted networks/subnets
Use Windows Firewall: New-NetFirewallRule -DisplayName 'Restrict DHCP' -Direction Inbound -Protocol UDP -LocalPort 67 -RemoteAddress 'TrustedSubnet' -Action Allow
Then block all other: New-NetFirewallRule -DisplayName 'Block DHCP' -Direction Inbound -Protocol UDP -LocalPort 67 -Action Block
Implement DHCP Relay Protection
allConfigure network devices to filter DHCP traffic and prevent malicious packets
🧯 If You Can't Patch
- Implement strict network segmentation to limit DHCP server exposure
- Deploy monitoring and alerting for DHCP service restarts/crashes
🔍 How to Verify
Check if Vulnerable:
Check if DHCP Server role is installed and running on Windows Server, then check Windows Update history for missing security patchesCheck Version:
Get-HotFix | Where-Object {$_.HotFixID -like 'KB*'} | Sort-Object InstalledOn -DescendingVerify Fix Applied:
Verify the security update KB number is installed via Windows Update history or Get-HotFix command📡 Detection & Monitoring
Log Indicators:
- DHCP service crash events in Windows Event Log (Event ID 7031, 7034)
- Unexpected DHCP service restarts
- High volume of malformed DHCP packets
Network Indicators:
- Unusual traffic patterns to UDP port 67
- DHCP packets with malformed options or unusual sizes
SIEM Query:
EventID=7031 OR EventID=7034 AND ServiceName='dhcpserver' | stats count by _time, host