Microsoft Defender AV must randomize scheduled task times.

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
medium	V-278659	SRG-APP-000278	WNDF-AV-000055	SV-278659r1144055_rule	2025-11-25	2

Description
In Microsoft Defender Antivirus, randomize the start time of the scan to any interval from 0 to 23 hours. By default, scheduled tasks begin at a random time within four hours of the time specified in Task Scheduler.

ℹ️ Check
Verify the policy value for Computer Configuration >> Administrative Templates >> Windows Components >> Microsoft Defender Antivirus >> Randomize scheduled task times is set to "Enabled"; otherwise, this is a finding. Procedure: Use the Windows Registry Editor to navigate to the following key: HKLM\Software\Policies\Microsoft\Windows Defender Criteria: If the value "RandomizeScheduleTaskTimes" is REG_DWORD = 1, this is not a finding. If the value is 0, this is a finding.

ℹ️ Check

Verify the policy value for Computer Configuration >> Administrative Templates >> Windows Components >> Microsoft Defender Antivirus >> Randomize scheduled task times is set to "Enabled"; otherwise, this is a finding. Procedure: Use the Windows Registry Editor to navigate to the following key: HKLM\Software\Policies\Microsoft\Windows Defender Criteria: If the value "RandomizeScheduleTaskTimes" is REG_DWORD = 1, this is not a finding. If the value is 0, this is a finding.

✔️ Fix
Set the policy value for Computer Configuration >> Administrative Templates >> Windows Components >> Microsoft Defender Antivirus >> Randomize scheduled task times to "Enabled". Click "OK". Click "Apply".