InformationNetwork Security Group Flow Logs should be enabled and the retention period is set to greater than or equal to 90 days.
Flow logs enable capturing information about IP traffic flowing in and out of network security groups. Logs can be used to check for anomalies and give insight into suspected breaches.
SolutionFrom Azure Console
Go to Network Watcher
Select NSG flow logs blade in the Logs section
Select each Network Security Group from the list
Ensure Status is set to On
Ensure Retention (days) setting greater than 90 days
Select your storage account in the Storage account field
Using Azure Command Line Interface 2.0
Enable the NSG flow logs and set the Retention (days) to greater than or equal to 90 days.
az network watcher flow-log configure --nsg <NameorID of the Network Security Group> --enabled true --resource-group <resourceGroupName> --retention 91 --storage-account <NameorID of the storage account to save flow logs>
By default, Network Security Group Flow Logs are disabled.