Azure Firewall Premium features

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Azure Firewall Premium is a next generation firewall with capabilities that are required for highly sensitive and regulated environments.

Azure Firewall Premium overview diagram

Azure Firewall Premium uses Firewall Policy, a global resource that can be used to centrally manage your firewalls using Azure Firewall Manager. Starting this release, all new features are configurable via Firewall Policy only. Firewall Rules (classic) continue to be supported and can be used to configure existing Standard Firewall features. Firewall Policy can be managed independently or with Azure Firewall Manager. A firewall policy associated with a single firewall has no charge.

Azure Firewall Premium includes the following features:

  • TLS inspection - decrypts outbound traffic, processes the data, then encrypts the data and sends it to the destination.
  • IDPS - A network intrusion detection and prevention system (IDPS) allows you to monitor network activities for malicious activity, log information about this activity, report it, and optionally attempt to block it.
  • URL filtering - extends Azure Firewall’s FQDN filtering capability to consider an entire URL. For example, www.contoso.com/a/c instead of www.contoso.com.
  • Web categories - administrators can allow or deny user access to website categories such as gambling websites, social media websites, and others.

TLS inspection

Azure Firewall Premium terminates outbound and east-west TLS connections. Inbound TLS inspection is supported with Azure Application Gateway allowing end-to-end encryption. Azure Firewall does the required value-added security functions and re-encrypts the traffic that is sent to the original destination.

Tip

TLS 1.0 and 1.1 are being deprecated and won’t be supported. TLS 1.0 and 1.1 versions of TLS/Secure Sockets Layer (SSL) have been found to be vulnerable, and while they still currently work to allow backwards compatibility, they aren't recommended. Migrate to TLS 1.2 as soon as possible.

To learn more about Azure Firewall Premium Intermediate CA certificate requirements, see Azure Firewall Premium certificates.

IDPS

A network intrusion detection and prevention system (IDPS) allows you to monitor your network for malicious activity, log information about this activity, report it, and optionally attempt to block it.

Azure Firewall Premium provides signature-based IDPS to allow rapid detection of attacks by looking for specific patterns, such as byte sequences in network traffic, or known malicious instruction sequences used by malware. The IDPS signatures are applicable for both application and network level traffic (Layers 4-7), they are fully managed, and continuously updated. IDPS can be applied to inbound, spoke-to-spoke (East-West), and outbound traffic.

The Azure Firewall signatures/rulesets include:

  • An emphasis on fingerprinting actual malware, Command and Control, exploit kits, and in the wild malicious activity missed by traditional prevention methods.
  • Over 35,000 rules in over 50 categories.
    • The categories include malware command and control, DoS attacks, botnets, informational events, exploits, vulnerabilities, SCADA network protocols, exploit kit activity, and more.
  • 20 to 40+ new rules are released each day.
  • Low false positive rating by using state-of-the-art malware sandbox and global sensor network feedback loop.

IDPS allows you to detect attacks in all ports and protocols for non-encrypted traffic. However, when HTTPS traffic needs to be inspected, Azure Firewall can use its TLS inspection capability to decrypt the traffic and better detect malicious activities.

The IDPS Bypass List allows you to not filter traffic to any of the IP addresses, ranges, and subnets specified in the bypass list.

You can also use signature rules when the IDPS mode is set to Alert, but there are one or more specific signatures that you want to block, including their associated traffic. In this case, you can add new signature rules by setting the TLS Inspection mode to deny.

URL filtering

URL filtering extends Azure Firewall’s FQDN filtering capability to consider an entire URL. For example, www.contoso.com/a/c instead of www.contoso.com.

URL Filtering can be applied both on HTTP and HTTPS traffic. When HTTPS traffic is inspected, Azure Firewall Premium can use its TLS inspection capability to decrypt the traffic and extract the target URL to validate whether access is permitted. TLS inspection requires opt-in at the application rule level. Once enabled, you can use URLs for filtering with HTTPS.

Web categories

Web categories lets administrators allow or deny user access to web site categories such as gambling websites, social media websites, and others. Web categories will also be included in Azure Firewall Standard, but it will be more fine-tuned in Azure Firewall Premium. As opposed to the Web categories capability in the Standard SKU that matches the category based on an FQDN, the Premium SKU matches the category according to the entire URL for both HTTP and HTTPS traffic.

For example, if Azure Firewall intercepts an HTTPS request for www.google.com/news, the following categorization is expected:

  • Firewall Standard – only the FQDN part will be examined, so www.google.com will be categorized as Search Engine.

  • Firewall Premium – the complete URL will be examined, so www.google.com/news will be categorized as News.

The categories are organized based on severity under Liability, High-Bandwidth, Business Use, Productivity Loss, General Surfing, and Uncategorized. For a detailed description of the web categories, see Azure Firewall web categories.

Web category logging

You can view traffic that has been filtered by Web categories in the Application logs. Web categories field is only displayed if it has been explicitly configured in your firewall policy application rules. For example, if you do not have a rule that explicitly denies Search Engines, and a user requests to go to www.bing.com, only a default deny message is displayed as opposed to a Web categories message. This is because the web category was not explicitly configured.

Category exceptions

You can create exceptions to your web category rules. Create a separate allow or deny rule collection with a higher priority within the rule collection group. For example, you can configure a rule collection that allows www.linkedin.com with priority 100, with a rule collection that denies Social networking with priority 200. This creates the exception for the pre-defined Social networking web category.

Supported regions

Azure Firewall Premium is supported in the following regions:

  • Australia Central (Public / Australia)
  • Australia Central 2 (Public / Australia)
  • Australia East (Public / Australia)
  • Australia Southeast (Public / Australia)
  • Brazil South (Public / Brazil)
  • Canada Central (Public / Canada)
  • Canada East (Public / Canada)
  • Central India (Public / India)
  • Central US (Public / United States)
  • Central US EUAP (Public / Canary (US))
  • East Asia (Public / Asia Pacific)
  • East US (Public / United States)
  • East US 2 (Public / United States)
  • France Central (Public / France)
  • France South (Public / France)
  • Germany West Central (Public / Germany)
  • Japan East (Public / Japan)
  • Japan West (Public / Japan)
  • Korea Central (Public / Korea)
  • Korea South (Public / Korea)
  • North Central US (Public / United States)
  • North Europe (Public / Europe)
  • Norway East (Public / Norway)
  • South Africa North (Public / South Africa)
  • South Central US (Public / United States)
  • South India (Public / India)
  • Southeast Asia (Public / Asia Pacific)
  • Switzerland North (Public / Switzerland)
  • UAE Central (Public / UAE)
  • UAE North (Public / UAE)
  • UK South (Public / United Kingdom)
  • UK West (Public / United Kingdom)
  • West Central US (Public / United States)
  • West Europe (Public / Europe)
  • West India (Public / India)
  • West US (Public / United States)
  • West US 2 (Public / United States)
  • West US 3 (Public / United States)

Known issues

Azure Firewall Premium has the following known issues:

Issue Description Mitigation
ESNI support for FQDN resolution in HTTPS Encrypted SNI isn't supported in HTTPS handshake. Today only Firefox supports ESNI through custom configuration. Suggested workaround is to disable this feature.
Client Certificates (TLS) Client certificates are used to build a mutual identity trust between the client and the server. Client certificates are used during a TLS negotiation. Azure firewall renegotiates a connection with the server and has no access to the private key of the client certificates. None
QUIC/HTTP3 QUIC is the new major version of HTTP. It's a UDP-based protocol over 80 (PLAN) and 443 (SSL). FQDN/URL/TLS inspection won't be supported. Configure passing UDP 80/443 as network rules.
Untrusted customer signed certificates Customer signed certificates are not trusted by the firewall once received from an intranet-based web server. A fix is being investigated.
Wrong source IP address in Alerts with IDPS for HTTP (without TLS inspection). When plain text HTTP traffic is in use, and IDPS issues a new alert, and the destination is public an IP address, the displayed source IP address is wrong (the internal IP address is displayed instead of the original IP address). A fix is being investigated.
Certificate Propagation After a CA certificate is applied on the firewall, it may take between 5-10 minutes for the certificate to take effect. A fix is being investigated.
TLS 1.3 support TLS 1.3 is partially supported. The TLS tunnel from client to the firewall is based on TLS 1.2, and from the firewall to the external Web server is based on TLS 1.3. Updates are being investigated.
KeyVault Private Endpoint KeyVault supports Private Endpoint access to limit its network exposure. Trusted Azure Services can bypass this limitation if an exception is configured as described in the KeyVault documentation. Azure Firewall is not currently listed as a trusted service and can't access the Key Vault. A fix is being investigated.

Next steps