Understanding Azure DNSSEC: Enhancing Security in DNS 💥

 

Introduction about Azure DNSSEC

The Domain Name System, or DNS, is the very foundation of modern networking, which translates human-readable domain names into IP addresses. While essential, DNS has conventionally been open to different types of security vulnerabilities, including DNS spoofing and cache poisoning. Azure DNSSEC-a Domain Name System Security Extensions-appends a layer of cryptographic security to DNS to handle these types of vulnerabilities. Please make a note currently the Azure DNSSEC feature is under preview stage. Soon Microsoft will bring that option general available.

Here, I will show in this blog what DNSSEC is, how it is implemented in Azure, and dive into the technical details necessary to understand and configure it accordingly.

What is DNSSEC

DNSSEC is an option that helps to maintain authentication and data integrity in the security aspect. This will use the Asymmetric key cryptography techniques to respond the DNS queries and protect from the DNS based attacks. This will include the digital signatures to bind with the DNS data using private and public key encryptions.

Key Benefits of DNSSEC

• Authentication
• Data Integrity
• Protection for DNS spoofing

How Azure Implements DNSSEC

Azure DNS now supports DNSSEC for public DNS zones, enabling organizations to protect their domains against several cyber-attacks and thus protect end-users. The Azure DNSSEC makes sure that the DNS zones are cryptographically signed and manages the keys used for signing DNS records.

Key Features of Azure DNSSEC:

Simplified Key Management: Azure will automatically create, rotate, and store DNSSEC keys.
Zone Signing: Azure DNS will sign DNS records for public zones using industry-standard algorithms.
Integration with Azure DNS: DNSSEC fits well into the Azure DNS service, making deployment and management easy.
Standard Compliance: It follows all the specifications of DNSSEC as defined in RFC 4033, RFC 4034, and RFC 4035.

How DNSSEC Works in Azure

1. Zone Signing
Key Signing Key (KSK): A long-term key used to sign the DNSKEY record holding the public keys for the zone.

Zone Signing Key (ZSK): A short-term key used to sign the actual DNS records in the zone.
Both KSKs and ZSKs are automatically managed by Azure, reducing the operational burden on the administrator.

2. Delegation Signer (DS) Record
After signing a zone, a DS record is generated. It is submitted to the parent zone-the .com or .org-to establish a chain of trust.

3. Query Validation
DNS clients or resolvers that support DNSSEC validate DNS responses by verifying the digital signatures using the public keys published in the DNSKEY record.
If the signatures are invalid or missing, the response is rejected.

Configuring DNSSEC in Azure

DNSSEC can be enabled in Azure via the following steps:

Step 1: Enable DNSSEC Zone

• Sign in to the Azure portal.
• Go to your Azure DNS zone.
• Under settings, click the DNSSEC option.
• Click the Enable DNSSEC button.

Step 2: Obtain the DS Record

• Upon enabling DNSSEC, Azure generates a DS record for the zone.
• Copy the DS record and 
• Copy the DS record and return it to your domain registrar.
• The registrar publishes this DS record in the parent zone to complete the chain of trust.

Step 3: Test DNSSEC Validation

Use tools like dnsviz.net or the dig command with the +dnssec option to validate that DNSSEC is correctly configured:

test.secops.test +dnssec

Test Analysis Tool: https://dnsviz.net

 Key Considerations for Azure DNSSEC

• Supported Zones: DNSSEC, in Azure, is available presently only for public DNS zones. DNSSEC is not supported for private DNS zones
• Registrar Support: Verify whether your domain registrar supports DNSSEC and if it will let you configure the DS records.
• Impact on Performance: Due to the signature verification aspect, DNSSEC adds overhead to DNS queries. Ensure that the DNS infrastructure is prepared to receive this additional load.
• Resolver Support: Not all DNS resolvers support DNSSEC validation. End-user experience may vary depending on their resolver's capabilities.
• Key Rotation: While Azure automates key rotation, organizations must monitor and validate the process as part of regular security audits.