Cis Azure Database 6.11

6.11 Ensure server parameter 'ssl_min_protocol_version' is set to 'TLSv1.2' or higher for PostgreSQL server (Automated)

Profile Applicability

• Level 1

Description

Note: It is not possible to set the minimal TLS version on PostgreSQL flexible server to lower than 1.2. Incoming connections which try to encrypt the traffic using TLS 1.0 and TLS 1.1 are denied.

Setting 'ssl_min_protocol_version' to 'TLSv1.2' or higher reduces TLS protocol vulnerabilities by preventing the use of significantly outdated versions of TLS.

Rationale

The Secure Sockets Layer (SSL) protocol encrypts network traffic transiting between server and client.

Using only the most recent versions of SSL protocols (TLS version 1.2 and higher) eliminates susceptibility to known exploited vulnerabilities of outdated versions of TLS. If TLS 1.2 does not provide additional granular configuration options for supported cipher suites, there's a chance that default ciphers which employ Cipher Block Chaining (CBC) mode may be enabled which would introduce Padding Oracle types of vulnerabilities. TLS 1.3 does not support CBC mode ciphers by default and by default supports GCM ciphers which include an extra authentication step during the clear text to cipher text encryption process.

TLS version 1.3 is preferable where it is possible to implement.

Versions 1.0 and 1.1 of TLS are no longer considered secure. These versions should not be used or permitted where data integrity and confidentiality are required.

Impact

TLS 1.3 is not compatible with older versions, so must be supported by all clients to be implemented.

Cipher suites may be able to be specified for TLS 1.2 if a premium SKU is in use.

Audit Procedure

Audit from Azure Portal

1. Login to Azure Portal using https://portal.azure.com.
2. Go to Azure Database for PostgreSQL servers.
3. For each server, under Settings, click Server parameters.
4. In the filter box, type ssl_min_protocol_version.
5. Ensure ssl_min_protocol_version is set to TLSV1.2 or higher.
6. Repeat steps 1-5 for each server.

Audit from Azure CLI

Run the following command to list PostgreSQL flexible servers:

az postgres flexible-server list

For each server, run the following command to get the ssl_min_protocol_version parameter value:

az postgres flexible-server parameter show --resource-group <resource-group> --server-name <server> --name ssl_min_protocol_version --query value

Ensure "TLSv1.2" or higher is returned.

Audit from PowerShell

Run the following command to list PostgreSQL flexible servers:

Get-AzPostgreSqlFlexibleServer

For each server, run the following command to get the ssl_min_protocol_version parameter value:

Get-AzPostgreSqlFlexibleServerConfiguration -ResourceGroupName <resource-group> -ServerName <server> -Name ssl_min_protocol_version | Select -p Value

Ensure TLSv1.2 or higher is returned.

Audit from Azure Policy

Policy ID: a43d5475-c569-45ce-a268-28fa79f4e87a Name: 'PostgreSQL flexible servers should be running TLS version 1.2 or newer'

Expected Result

The ssl_min_protocol_version should be set to TLSv1.2 or higher.

Remediation

Remediate from Azure Portal

1. Login to Azure Portal using https://portal.azure.com.
2. Go to Azure Database for PostgreSQL servers.
3. For each server, under Settings, click Server parameters.
4. In the filter box, type ssl_min_protocol_version.
5. Set ssl_min_protocol_version to TLSV1.2 or higher.
6. Select Save.
7. Repeat steps 1-6 for each server requiring remediation.

Remediate from Azure CLI

For each server requiring remediation, run the following command to set ssl_min_protocol_version to TLSv1.2 or higher:

az postgres flexible-server parameter set --resource-group <resource-group> --server-name <server> --name ssl_min_protocol_version --value TLSv1.2

Remediate from PowerShell

For each server requiring remediation, run the following command to set ssl_min_protocol_version to TLSv1.2 or higher:

Update-AzPostgreSqlFlexibleServerConfiguration -ResourceGroupName <resource-group> -ServerName <server> -Name ssl_min_protocol_version -Value TLSv1.2

Default Value

By default, ssl_min_protocol_version is set to TLSv1.2.

References

1. https://learn.microsoft.com/en-us/azure/postgresql/flexible-server/security-connect-tls
2. https://learn.microsoft.com/en-us/azure/postgresql/security/security-tls

Profile

• Level 1