Microsoft Defender AV must use advanced protection against ransomware.

Documentable No

Rule ID SV-278650r1144036_rule

CCI References

CCI-001170

Discussion

This policy setting provides an extra layer of protection against ransomware. It uses both client and cloud heuristics to determine whether a file resembles ransomware. This rule doesn't block files that have one or more of the following characteristics: - The file is found to be unharmful in the Microsoft cloud. - The file is a valid signed file. - The file is prevalent enough to not be considered as ransomware. - The rule tends to err on the side of caution to prevent ransomware.

Check Procedure

Verify the policy value for Computer Configuration >> Administrative Templates >> Windows Components >> Microsoft Defender Antivirus >> Microsoft Defender Exploit Guard >> Attack Surface Reduction >> Configure Attack Surface Reduction rules is set to "Enabled".

Procedure: Use the Windows Registry Editor to navigate to the following key: 
HKLM\Software\Policies\Microsoft\Windows Defender\Windows Defender Exploit Guard\ASR\Rules

Criteria: If the value "c1db55ab-c21a-4637-bb3f-a12568109d35" is REG_SZ = 1, this is not a finding.

If the value is other than 1, this is a finding.

Fix Action

Set the policy value for Computer Configuration >> Administrative Templates >> Windows Components >> Microsoft Defender Antivirus >> Microsoft Defender Exploit Guard >> Attack Surface Reduction >> Configure Attack Surface Reduction rules to "Enabled".

Under the policy option "Set the state for each ASR rule:", then click "Show".

Enter GUID "c1db55ab-c21a-4637-bb3f-a12568109d35" in the "Value Name" column.

Enter "1" in the "Value" column.

Click "OK".

Click "Apply".