Information
Ensure that network flow logs are captured and fed into a central log analytics workspace.
Retirement Notice
On September 30, 2027, network security group (NSG) flow logs will be retired. Starting June 30, 2025, it will no longer be possible to create new NSG flow logs. Azure recommends migrating to virtual network flow logs. Review
https://azure.microsoft.com/en-gb/updates?id=Azure-NSG-flow-logs-Retirement
for more information.
For virtual network flow logs, consider applying the recommendation Ensure that virtual network flow logs are captured and sent to Log Analytics in this section.
Network Flow Logs provide valuable insight into the flow of traffic around your network and feed into both Azure Monitor and Azure Sentinel (if in use), permitting the generation of visual flow diagrams to aid with analyzing for lateral movement, etc.
NOTE: Nessus has not performed this check. Please review the benchmark to ensure target compliance.
Solution
Remediate from Azure Portal
- Navigate to Network Watcher
- Under Logs select Flow logs
- Select + Create
- Select the desired Subscription.
- For Flow log type select Network security group
- Select + Select target resource
- Select Network security group
- Select a network security group.
- Click Confirm selection
- Select or create a new Storage Account.
- If using a v2 storage account, input the retention in days to retain the log.
- Click Next
- Under Analytics for Flow log version select Version 2
- Check the box next to Enable traffic analytics
- Select a processing interval.
- Select a Log Analytics Workspace
- Select Next
- Optionally add Tags.
- Select Review + create
- Select Create
Warning
The remediation policy creates remediation deployment and names them by concatenating the subscription name and the resource group name. The MAXIMUM permitted length of a deployment name is 64 characters. Exceeding this will cause the remediation task to fail.
Impact:
The impact of configuring NSG Flow logs is primarily one of cost and configuration. If deployed, it will create storage accounts that hold minimal amounts of data on a 5-day lifecycle before feeding to Log Analytics Workspace.This will increase the amount of data stored and used by Azure Monitor.