Cis Azure Database 5.7

5.7 Ensure server parameter 'error_server_log_file' is Enabled for MySQL Database Server (Manual)

Profile Applicability

• Level 2

Description

Enable error logs on MySQL flexible servers.

Rationale

With error_server_log_file enabled, MySQL Database will log database errors to a logging solution. These logs assist in producing a forensic trail that can be used for investigation or for detection when paired with a SIEM.

Impact

There are further costs incurred for storage of logs. For high traffic databases these logs will be significant. Determine your organization's needs before enabling.

Audit

Audit from Azure Portal

1. Login to Azure Portal using https://portal.azure.com.
2. Go to Azure Database for MySQL Servers.
3. For each database, under Settings, click Server parameters.
4. In the row under Save, select All.
5. In the filter bar, type error_server_log_file.
6. Ensure that the VALUE for error_server_log_file is ON.

Audit from PowerShell

Ensure the below command returns a Value of on:

Get-AzMySqlFlexibleServerConfiguration -ResourceGroupName <resourceGroup> -ServerName <serverName> -Name error_server_log_file

Expected Result

The error_server_log_file server parameter should return a value of ON.

Remediation

Remediate from Azure Portal

Part 1 - Turn on audit logs

1. Login to Azure Portal using https://portal.azure.com.
2. Go to Azure Database for MySQL flexible servers.
3. For each database, under Settings, click Server parameters.
4. Set error_server_log_file to ON.
5. Click Save.

Part 2 - Capture audit logs (diagnostic settings is for example only, send these logs to the appropriate data sink for your logging needs)

1. Under Monitoring, select Diagnostic settings.
2. Select + Add diagnostic setting.
3. Provide a diagnostic setting name.
4. Under Categories, select MySQL Audit Logs.
5. Specify destination details.
6. Click Save.

It may take up to 10 minutes for the logs to appear in the configured destination.

Remediate from PowerShell

Use the below command to enable error_server_log_file:

Update-AzMySqlFlexibleServerConfiguration -ResourceGroupName <resourceGroup> -ServerName <serverName> -Name error_server_log_file -Value on

Default Value

error_server_log_file is set to OFF by default.

References

1. https://learn.microsoft.com/en-us/azure/mysql/flexible-server/tutorial-configure-audit
2. https://learn.microsoft.com/en-us/security/benchmark/azure/mcsb-logging-threat-detection#lt-3-enable-logging-for-security-investigation
3. https://learn.microsoft.com/en-us/azure/mysql/flexible-server/concepts-error-logs

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