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Behavior:Win32/WDBlockFirewallRule.S
Aliases: No associated aliases
Summary
This detection is for the unauthorized modification of Microsoft Defender Firewall rules made by threats to block critical security processes from accessing the network. Microsoft 365 Defender components require network access for important features and services, such as cloud-delivered protection and security intelligence updates.
When Microsoft Defender Antivirus detects malicious modification of firewall rules in enterprise environments, it automatically removes rules that are tampered with. For home users, these rules are automatically removed only if tamper protection is enabled in the Windows Security Center app. Learn how to protect your security settings by enabling tamper protection.
The Microsoft Defender Firewall service must be restarted to complete repairs. If more than one firewall rule was tampered with, you may see additional alerts for the detection Trojan:Win32/BlockMsav.A!reg after restarting the system.
Microsoft Defender Antivirus automatically removes threats as they are detected. However, many infections can leave remnant files and system changes. Updating your antimalware definitions and running a full scan might help address these remnant artifacts.
You can also visit our advanced troubleshooting page or search the Microsoft virus and malware community for more help.
Secure configuration
To get the best and fastest protection from Microsoft Defender Antivirus, ensure it can connect to the cloud protection service. Use the Windows search box to find and open your Virus & threat protection settings and turn on the following cloud-delivered protection and automatic sample submission. For more information, read:
- Use Microsoft Defender Antivirus cloud-delivered protection
- Configure and validate Microsoft Defender Antivirus network connections
Learn how to manage connections to Microsoft services:
