Orchestrating Intrusion Detection and Prevention Signature overrides in Azure Firewall Premium
Introduction: Azure Firewall Premium provides strong protection with a built-in Intrusion Detection and Prevention System (IDPS). It inspects inbound, outbound, and east-west traffic against Microsoft’s continuously updated signature set and can block threats before they reach your workloads. IDPS works out of the box without manual intervention. However, in many environments administrators need the flexibility to override specific signatures to better align with operational or security requirements. Common reasons include: Compliance enforcement – enforcing policies that require certain threats (such as High severity signatures) to always be blocked, directional tuning or protocol/category-based tuning. Incident response – reacting quickly to emerging vulnerabilities by enabling blocking for newly relevant signatures. Noise reduction – keeping informational signatures in alert mode to avoid false positives while still maintaining visibility. In many environments, signature overrides are typically managed in one of two ways: Using the global IDPS mode Using the Azure portal to apply per-signature overrides individually While these approaches work, managing overrides manually becomes difficult when thousands of signatures are involved. The Azure portal also limits the number of changes that can be applied at once, which makes large tuning operations time-consuming. To simplify this process, this blog introduces an automation approach that allows you to export, filter, and apply IDPS signature overrides in bulk using PowerShell scripts. A Common Operational Scenario: Consider the following scenario frequently encountered by security teams: Scenario A security team wants to move their firewall from Alert → Alert + Deny globally to strengthen threat prevention. However, they do not want Low severity signatures to Deny traffic, because these signatures are primarily informational and may create unnecessary noise or false positives. Example: Signature ID: 2014906 Severity: Low Description: INFO – .exe File requested over FTP This signature is classified as informational because requesting an .exe file over FTP indicates contextual risk, not necessarily confirmed malicious activity. If the global mode is switched to Alert + Deny, this signature may start blocking traffic unnecessarily. The goal therefore becomes: Enable Alert + Deny globally Keep Low severity signatures in Alert mode The workflow described in this blog demonstrates how to achieve this outcome using the IDPS Override script. Automation Workflow: The automation process uses two scripts to export and update signatures. Workflow overview Azure Firewall Policy │ ▼ Export Signatures (ipssigs.ps1) │ ▼ CSV Review / Edit │ ▼ Bulk Update (ipssigupdate.ps1) │ ▼ Updated Firewall Policy Before implementing the workflow, it’s helpful to review the available IDPS modes and severity as seen below, very briefly. IDPS Modes: Severity: Prerequisites: Now that we understand Azure Firewall IDPS concepts and have the context for this script, let's get started with the workings of the script itself. First of all, let us ensure that you are connected to your Azure account and have selected the correct subscription. You can do so by running the following command: Connect-AzAccount -Subscription "<your-subscription-id>" Ensure the following modules are installed which are required for this operation: Az.Accounts Az.Network 💡 Tip: You can check if the above modules are installed by running the following command: Get-Module -ListAvailable Az* or check specific modules using this following commands: Get-module Az.Network | select Name, Version, Path Get-module Az.Accounts | select Name, Version, Path If you need to install/import them, run the following command which downloads all generally available Azure service modules from the PowerShell Gallery, overwriting existing versions without prompting: Import-Module Az.Network Import-Module Az.Accounts Restart PowerShell after installation. Configure ipsconfig.json Now, let's configure the ipsconfig.json file and ensure the configuration file contains your target environment details i.e., target subscription, target firewall policy resource group name, firewall name, firewall policy name, location and rule collection group name. Example: { "subs": "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx", "rg": "TEST-RG", "fw": "fw", "fwp": "fw-policy", "location": "CentralUS", "rcg": "DefaultNetworkRuleCollectionGroup" } Note: Your account must have permissions to read and update firewall policy and IDPS settings. Running the Script: 1. Export Signatures Now that we have all the prerequisites ready, it's time to run the script. Run the following command in PS in the directory where the script exists: .\ipssigs.ps1 Now, the script should prompt for filtering criteria as shown below and you can input the values as per your requirements: For the example scenario that we considered, we will give the following inputs as shown above in the snapshot: Mode: Alert Severity: Low 💡 Tip: When specifying multiple values, ensure there is space between the 2 values but no comma, otherwise the script may return no results. The script now exports the results to ipssignatures_results.csv file by default (or a custom filename if specified). The exported CSV includes metadata such as severity, direction, group, and protocol, which can help inform tuning decisions. 2. Prepare the CSV Now, we do not need all of these columns when inputting the CSV file to update the Firewall Policy. We only need the following columns. Signature Id Mode Therefore, we will need to remove all other columns while keeping the SignatureId and mode columns along with their headers as seen below: 3. Update the Firewall Policy Now, it's time to update the Firewall Policy with the signature/mode overrides that we need using the above CSV file. However, please note that the script supports two operations: Changing the global IDPS mode Applying bulk signature overrides using the CSV file You can use either option independently or both together. Let's understand this further by looking at these 2 examples. Example 1: Change Global Mode and Override Low Severity Signatures Goal: Set global mode to Alert + Deny Keep Low severity signatures in Alert Command: .\ipssigupdate.ps1 -GlobalMode Deny -InputFile Lowseveritysignatures.csv Result: High and Medium signatures → Alert + Deny Low signatures → Alert Example 2: Override Signatures Only If the global mode should remain unchanged, then run the following command only. .\ipssigupdate.ps1 The script will then prompt for the input CSV file in the next step as seen below: As seen the changed were made to the Azure Firewall in just a few seconds. After the script completes, updated signature actions should appear in the firewall policy. 4. Monitoring Script Execution Please use the following commands to track and monitor the background processes, to verify the status, check for any error and remove completed jobs as seen below: You can check background job status using: Get-Job -Id <#> View results: Receive-Job -Id <#> -Keep Remove completed jobs: Remove-Job -Id <#> Note: Up to 10,000 IDPS rules can be customized at a time 5. Validate the Changes: Now that we finished running the script, it's time to verify the update by confirming: Global IDPS mode in the firewall policy Signature override state Alert or block events in your logging destination (Log Analytics or Microsoft Sentinel) Note: Please note that, while most signatures support Off, Alert, or Deny actions, there are some context-setting signatures, that have fixed actions and cannot be overridden. Conclusion: Azure Firewall Premium makes it straightforward to apply broad IDPS configuration changes through the Azure portal. However, as environments scale, administrators often require more precise and repeatable ways to manage signature tuning. The automation approach described in this blog allows administrators to query, review, and update thousands of signatures in minutes. This enables repeatable tuning workflows, improves operational efficiency, and simplifies large-scale security configuration changes. References: Github Repository for the IDPS scripts Azure Firewall IDPS Azure Firewall IDPS signature rule categoriesAssess Azure DDoS Protection Status Across Your Environment
Introduction Distributed Denial of Service (DDoS) attacks continue to be one of the most prevalent threats facing organizations with internet-facing workloads. Azure DDoS Protection provides cloud-scale protection against L3/4 volumetric attacks, helping ensure your applications remain available during an attack. However, as Azure environments grow, maintaining visibility into which resources are protected and whether diagnostic logging is properly configured becomes increasingly challenging. Security teams often struggle to answer basic questions: Which Public IP addresses are protected by Azure DDoS Protection? Are we using IP Protection or Network Protection (DDoS Protection Plan)? Is diagnostic logging enabled for protected resources? To address these questions at scale, we’ve developed a PowerShell script that assesses your Azure DDoS Protection posture across all subscriptions. Understanding Azure DDoS Protection SKUs Azure offers three DDoS Protection tiers: Protection Type Description Scope Network Protection Enterprise-grade protection via a DDoS Protection Plan attached to VNETs All Public IPs in protected VNETs IP Protection Per-IP protection for individual Public IP addresses Individual Public IP For more details, see Azure DDoS Protection overview. The Assessment Script The Check-DDoSProtection.ps1 script provides a full view of DDoS Protection status across your Azure environment. This section covers the script’s key capabilities and the resource types it supports. Key Features Multi-subscription support: Scan a single subscription or all subscriptions you have access to DDoS Protection status: Identifies which Public IPs are protected and which SKU is being used VNET correlation: Automatically determines the VNET associated with each Public IP to assess Network Protection inheritance Diagnostic logging check: Verifies if DDoS diagnostic logs are configured for protected resources CSV export: Export results for further analysis or reporting Prerequisites Before running the script, ensure you have: Azure PowerShell modules installed: Run the following commands in PowerShell (version 5.1+) or PowerShell Core to install the required Azure modules. No special permissions are needed, these will install in your user profile. Install-Module -Name Az.Accounts -Scope CurrentUser -Force Install-Module -Name Az.Network -Scope CurrentUser -Force Install-Module -Name Az.Monitor -Scope CurrentUser -Force Appropriate Azure permissions: o Reader role on subscriptions you want to scan o Microsoft.Network/publicIPAddresses/read o Microsoft.Network/virtualNetworks/read o Microsoft.Insights/diagnosticSettings/read Azure login: Authenticate to Azure before running the script. This opens a browser window for interactive sign-in. Connect-AzAccount How to Use the Script Run the script from a PowerShell session where you’ve already authenticated with Connect-AzAccount. The account must have Reader role on the subscriptions you want to scan. Download the Script You can download the script from: - GitHub: Check-DDoSProtection.ps1 Basic Usage: Scan Current Subscription Scans only the subscription currently selected in your Azure context. .\Check-DDoSProtection.ps1 Scan a Specific Subscription Scans a single subscription by its ID. .\Check-DDoSProtection.ps1 -SubscriptionId "12345678-1234-1234-1234-123456789012" Scan All Subscriptions Scans every subscription your account has Reader access to. .\Check-DDoSProtection.ps1 -AllSubscriptions Export Results to CSV Exports the assessment results to a CSV file for reporting or further analysis. .\Check-DDoSProtection.ps1 -AllSubscriptions -ExportPath "C:\Reports\DDoS-Report.csv" Large Environment Options For organizations with many subscriptions or thousands of Public IPs, use the following parameters to handle errors gracefully and avoid API throttling. .\Check-DDoSProtection.ps1 -AllSubscriptions ` -ContinueOnError ` -SavePerSubscription ` -ExportPath "C:\Reports\DDoS-Report.csv" ` -ThrottleDelayMs 200 Parameters for large environments: Parameter Description -ContinueOnError Continue scanning even if a subscription fails (e.g., access denied) -SavePerSubscription Save a separate CSV file for each subscription -ThrottleDelayMs Delay between API calls to avoid throttling (default: 100ms) Understanding the Output The script provides both console output and optional CSV export. This section covers what each output type contains. Console Output The script displays a summary table for each subscription: Summary Statistics At the end of each subscription scan: CSV Export Columns Column Description Subscription Name of the Azure subscription Public IP Name Name of the Public IP resource Resource Group Resource group containing the Public IP Location Azure region IP Address Actual IP address (or “Dynamic” if not allocated) IP SKU Basic or Standard DDoS Protected Yes/No Risk Level High (unprotected) / Low (protected) DDoS SKU Network Protection, IP Protection, or None DDoS Plan Name Name of the DDoS Protection Plan (if applicable) VNET Name Associated Virtual Network name Associated Resource Resource the Public IP is attached to Resource Type Type of associated resource (VM, AppGw, LB, etc.) Diagnostic Logging Configured/Not Configured/N/A Log Destination Log Analytics, Storage, Event Hub, or None Recommendation Suggested action for unprotected resources Sample Scenarios Scenario 1: Protected Application Gateway Public IP Name: appgw-frontend-pip DDoS Protected: Yes DDoS SKU: Network Protection DDoS Plan Name: contoso-ddos-plan VNET Name: production-vnet Diagnostic Logging: Configured (Log Analytics) Risk Level: Low Explanation: The Application Gateway’s Public IP inherits protection from the VNET which has a DDoS Protection Plan attached. Diagnostic logging is properly configured. Scenario 2: Unprotected External Load Balancer Public IP Name: external-lb-pip DDoS Protected: No DDoS SKU: VNET not protected VNET Name: (External LB) Diagnostic Logging: N/A Risk Level: High Recommendation: Enable DDoS Protection on associated VNET or enable IP Protection Explanation: This external Load Balancer’s Public IP is not in a protected VNET. The script flags this as high risk. Scenario 3: IP Protection Without Logging Public IP Name: standalone-api-pip DDoS Protected: Yes DDoS SKU: IP Protection VNET Name: - Diagnostic Logging: Not Configured Risk Level: Low Recommendation: Configure diagnostic logging for DDoS-protected resources Explanation: The IP has IP Protection enabled, but diagnostic logging is not configured. While protected, you won’t have visibility into attack telemetry. Troubleshooting Script Doesn’t Find All Subscriptions Use the following command to list your Azure role assignments and verify you have Reader access to the target subscriptions. Run this from Azure Cloud Shell or a local PowerShell session after authenticating with Connect-AzAccount. # Check your role assignments Get-AzRoleAssignment -SignInName (Get-AzContext).Account.Id | Select-Object Scope, RoleDefinitionName API Throttling The script includes built-in retry logic for API throttling. If you still experience rate limit errors, increase the delay between API calls. Run this from the directory containing the script. .\Check-DDoSProtection.ps1 -AllSubscriptions -ThrottleDelayMs 500 Access Denied for Specific Resources The script displays “(Access Denied)” for VNETs or resources you don’t have permission to read. This doesn’t affect the overall assessment but may result in incomplete VNET information. Summary This guide covered how to use the Check-DDoSProtection.ps1 script to identify unprotected Public IP addresses, determine which DDoS SKU (Network Protection vs. IP Protection) is in use, verify diagnostic logging configuration, and assess risk levels across all subscriptions. Running this script periodically helps security teams track protection coverage as their Azure environment evolves. Related Resources Azure DDoS Protection Overview Azure DDoS Protection SKU Comparison Configure DDoS Protection Diagnostic Logging Best Practices for Azure DDoS Protection Zero Trust with Azure DDoS Protection
Detect, correlate, contain: New Azure Firewall IDPS detections in Microsoft Sentinel and XDR
As threat actors continue to blend reconnaissance, exploitation, and post-compromise activity, network-level signals remain critical for early detection and correlated response. To strengthen this layer, we're introducing five new Azure Firewall IDPS detections, now available out of the box in the Azure Firewall solution for Microsoft Sentinel and Microsoft Defender XDR. See It in Action This short demo walks through Azure Firewall's IDPS capabilities, the new Sentinel detections, and the automated response playbook — from malicious traffic hitting the firewall to the threat being contained without manual intervention. Watch the demo → Azure Firewall integration with Microsoft Sentinel and Defender XDR Read on for the full details on each detection, customization options, and a step-by-step walkthrough of the automated response workflow. What’s new The Azure Firewall solution now includes five new analytic detections built on Azure Firewall. Detection name What it detects (network signal) MITRE ATT&CK tactic(s) Example ATT&CK techniques (representative) SOC impact High severity malicious activity Repeated high confidence IDPS hits such as exploit kits, malware C2, credential theft, trojans, shellcode delivery Initial access (TA0001) execution (TA0002) Command and Control (TA0011) Exploit public facing application (T1190) command and control over web protocols (T1071.001) Ingress Tool Transfer (T1105) Highlights active exploitation or post compromise behavior at the network layer; strong pivot point into XDR investigations Elevation of privilege attempt Repeated attempts or success gaining user or administrator privileges Privilege escalation (TA0004) Exploitation for privilege escalation (T1068) Flags critical inflection points where attackers move from foothold to higher impact control Web application attack Probing or exploitation attempts against web applications Initial access (TA0001) Exploit public facing application (T1190) Surfaces external attack pressure against internet facing apps protected by Azure Firewall Medium severity malicious activity Potentially unwanted programs, crypto mining, social engineering indicators, suspicious filenames/system calls Initial access (TA0001) execution (TA0002) impact (TA0040) User Execution (T1204) Resource Hijacking (T1496) Early stage or lower confidence signals that help teams hunt, monitor, and tune response before escalation Denial of Service (DoS) attack Attempted or sustained denial of service traffic patterns Impact (TA0040) Network Denial of Service (T1498) Enables faster DoS identification and escalation, reducing time to mitigation Where these detections apply These detections are available through the Azure Firewall solution in: Microsoft Sentinel, enabling SOC centric investigation, hunting, and automation Microsoft Defender XDR, allowing network level signals to participate in end-to-end attack correlation across identity, endpoint, cloud, and email They are powered by the AZFWIdpsSignature log table and require Azure Firewall with IDPS enabled (preferably with TLS inspection). Customizing the detections to fit your environment The Azure Firewall IDPS detections included in the Microsoft Sentinel solution are designed to be fully adaptable to customer environments, allowing SOC teams to tune sensitivity, scope, and signal fidelity based on their risk tolerance and operational maturity. Each detection is built on the AZFWIdpsSignature log table and exposes several clearly defined parameters that customers can modify without rewriting the analytic logic. 1. Tune alert sensitivity and time horizon Customers can adjust the lookback period (TimeWindow) and minimum hit count (HitThreshold) to control how aggressively the detection triggers. Shorter windows and lower thresholds surface faster alerts for high-risk environments, while longer windows and higher thresholds help reduce noise in high volume networks. 2. Align severity with internal risk models Each analytic rule includes a configurable minimum severity (MinSeverity) aligned to Azure Firewall IDPS severity scoring. Organizations can raise or lower this value to match internal incident classification standards and escalation policies. 3. Focus on relevant threat categories and behaviors Optional filters allow detections to be scoped to specific threat categories, descriptions, or enforcement actions. Customers can enable or disable: Category filtering to focus on specific attack classes (for example, command and control, exploit kits, denial of service, or privilege escalation). Description filtering to target specific behavioral patterns. Action filtering to alert only on denied or alerted traffic versus purely observed activity. This flexibility makes it easy to tailor detections for different deployment scenarios such as internet facing workloads, internal east-west traffic monitoring, or regulated environments with stricter alerting requirements. 4. Preserve structure while customizing output Even with customization, the detections retain consistent enrichment fields including source IP, threat category, hit count, severity, actions taken, and signature IDs ensuring alerts remain actionable and easy to correlate across Microsoft Sentinel and Microsoft Defender XDR workflows. By allowing customers to tune thresholds, scope, and focus areas while preserving analytic intent, these Azure Firewall IDPS detections provide a strong out of the box baseline that can evolve alongside an organization’s threat landscape and SOC maturity. Automated detection and response for Azure Firewall using Microsoft Sentinel In this walkthrough, we’ll follow a real-world attack simulation and see how Azure Firewall, Microsoft Sentinel, and an automated playbook work together to detect, respond to, and contain malicious activity, without manual intervention. Step 1: Malicious traffic originates from a compromised source A source IP address 10.0.100.20, hosted within a virtual network, attempts to reach a web application protected by Azure Firewall. To validate the scenario, we intentionally generate malicious outbound traffic from this source, such as payloads that match known attack patterns. This is an outbound flow, meaning the traffic is leaving the internal network and attempting to reach an external destination through Azure Firewall. At this stage: Azure Firewall is acting as the central enforcement point Traffic is still allowed, but deep packet inspection is in effect Step 2: Azure Firewall IDPS detects malicious behavior Azure Firewall's intrusion detection and prevention system (IDPS) is enabled and inspects traffic as it passes through the firewall. When IDPS detects patterns that match known malicious signatures, the action taken depends on the signature's configured mode: Alert mode: IDPS generates a detailed security log for the matched signature but allows the traffic to continue. This is useful for monitoring and tuning before enforcing blocks. Alert and Deny mode: IDPS blocks the matching traffic and generates a detailed security log. The threat is stopped at the network layer while full telemetry is preserved for investigation. In both cases, IDPS records rich metadata including source IP, destination, protocol, signature name, severity, and threat category. These logs are what power the downstream detections in Microsoft Sentinel. In this walkthrough, the signature is configured in Alert and Deny mode, meaning the malicious traffic from 10.0.100.20 is blocked immediately at the firewall while the corresponding log is forwarded for analysis. Step 3: Firewall logs are sent to Log Analytics All Azure Firewall logs, including IDPS logs, are sent to a Log Analytics workspace named law-cxeinstance. At this point: Firewall logs are centralized Logs are normalized and can be queried No alerting has happened yet, only data collection This workspace becomes the single source of truth for downstream analytics and detections. Step 4: Microsoft Sentinel ingests and analyzes the Firewall logs The Log Analytics workspace is connected to Microsoft Sentinel, which continuously analyzes incoming data. Using the Azure Firewall solution from the Sentinel Content Hub, we previously deployed a set of built-in analytic rule templates designed specifically for Firewall telemetry. One of these rules is: “High severity malicious activity detected”. This rule evaluates IDPS logs and looks for: High-confidence signatures, known exploit techniques and malicious categories identified by Firewall IDPS. Step 5: Sentinel creates an incident When the analytic rules are met, Microsoft Sentinel automatically: Raises an alert Groups related alerts into an incident Extracts entities such as IP addresses, severity, and evidence In this case, the source IP 10.0.100.20 is clearly identified as the malicious actor and attached as an IP entity to the incident. This marks the transition from detection to response. Step 6: An automation rule triggers the playbook To avoid manual response, we configured a Sentinel automation rule that triggers whenever: An incident is created The analytic rule name matches any of the analytic rules we configured The automation rule immediately triggers a Logic App playbook named AzureFirewallBlockIPaddToIPGroup. This playbook is available as part of the Azure Firewall solution and can be deployed directly from the solution package. In addition, a simplified version of the playbook is published in our GitHub repository, allowing you to deploy it directly to your resource group using the provided ARM template. This is where automated containment begins. Step 7: The playbook aggregates and updates the IP Group The playbook performs several critical actions in sequence: Extracts IP entities from the Sentinel incident Retrieves the existing Azure Firewall IP Group named MaliciousIPs Checks for duplicates to avoid unnecessary updates Aggregates new IPs into a single array/list Updates the IP Group in a single operation. It is important to note that the playbook managed identity should have contributor access on the IP Group or its resource group to perform this action. In our scenario, the IP 10.0.100.20 is added to the MaliciousIPs IP Group. Step 8: Firewall policy enforces the block immediately Azure Firewall already has a network rule named BlockMaliciousTraffic configured with: Source: MaliciousIPs IP Group Destination: Any Protocol: Any Action: Deny Because the rule references the IP Group dynamically, the moment the playbook updates MaliciousIPs, the firewall enforcement takes effect instantly — without modifying the rule itself. Traffic originating from 10.0.100.20 is now fully blocked, preventing any further probing or communication with the destination. The threat has been effectively contained. When a SOC analyst opens the Sentinel incident, they see that containment has already occurred: the malicious IP was identified, the IP Group was updated, and the firewall block is in effect — all with a full audit trail of every automated action taken, from detection through response. No manual intervention was required. Conclusion With these five new IDPS detections, Azure Firewall closes the gap between network-level signal and SOC-level action. Raw signature telemetry is automatically transformed into severity-aware, MITRE ATT&CK-mapped alerts inside Microsoft Sentinel and Microsoft Defender XDR — giving security teams correlated, investigation-ready incidents instead of isolated log entries. Combined with automation playbooks, the result is a fully integrated detect-and-respond workflow: Azure Firewall identifies malicious behavior, Sentinel raises and enriches the incident, and a Logic App playbook contains the threat by updating firewall policy in real time — all without manual intervention. These detections are included at no additional cost. Simply install the Azure Firewall solution from the Microsoft Sentinel Content Hub, and the analytic rules automatically appear in your Sentinel workspace — ready to enable, customize, and operationalize. Get started today: Azure Firewall with Microsoft Sentinel overview Automate Threat Response with Playbooks in Microsoft Sentinel Azure Firewall Premium features implementation guide Recent real‑world breaches underscore why these detections matter. Over the past year, attackers have repeatedly gained initial access by exploiting public‑facing applications, followed by command‑and‑control activity, web shell deployment, cryptomining, and denial‑of‑service attacks. Incidents such as the GoAnywhere MFT exploitation, widespread web‑application intrusions observed by Cisco Talos, and large‑scale cryptomining campaigns against exposed cloud services demonstrate the value of correlating repeated network‑level malicious signals. The new Azure Firewall IDPS detections are designed to surface these patterns early, reduce alert noise, and feed high‑confidence network signals directly into Microsoft Sentinel and Microsoft Defender XDR for faster investigation and response. Your network telemetry is a first-class security signal - let it work for you! Visit us at RSA 2026 to see the full detection-to-containment workflow live.Azure Bastion: Enterprise-grade secure access made simple
Managing secure remote access to virtual machines traditionally means juggling public IP addresses, configuring jump boxes, deploying VPN infrastructure, and managing complex firewall rules. Each layer adds cost, complexity, and potential security vulnerabilities. Azure Bastion changes everything. It's a fully managed PaaS service that provides secure RDP/SSH connectivity to Azure VMs directly through the Azure portal, without exposing VMs to the public internet. No public IPs, no jump boxes, no VPN clients. Azure Bastion isn't one-size-fits-all. Whether you're running a development sandbox, managing production workloads at scale, or operating in regulated industries with strict compliance requirements, there's a Bastion SKU designed for your specific needs. Basic SKU for small production workloads with browser-based access. Ideal for small businesses, startups, or single-application environments with limited concurrent users (up to 2 instances). Standard SKU for scalable production environments requiring VNet peering, native client and shareable links for non-portal access. Supports up to 50 scale units, perfect for growing organizations and multi-VNET architectures. Premium SKU for regulated industries requiring session recording for compliance (HIPAA, SOX, PCI-DSS, FDA), private-only deployment for zero internet exposure. Essential for healthcare, finance, pharmaceuticals, government, and air-gapped environments. Let's dive into real-world scenarios that showcase how Azure Bastion simplifies enterprise-grade secure access. Real-World Scenarios: Azure Bastion features are best understood through real-world application. In the scenarios below, we'll tackle three common enterprise challenges with remote secure access. Let's see Azure Bastion in action. Scenario 1: Instant Vendor Access Without the Hassle The Challenge: It's 3 PM on Friday when your production database experiences critical performance issues. An external DBA consultant needs immediate access to investigate, but your organization faces a familiar dilemma. The traditional provisioning process requires creating a temporary Azure AD account, configuring VPN access and credentials, coordinating with the security team for approvals, and ensuring timely revocation after the engagement concludes. Even with expedited processes, this takes 2-3 hours—and there's always the risk of lingering permissions if revocation is overlooked. By the time access is provisioned, it's often too late to resolve the issue before the weekend, leaving your production environment vulnerable and your team working overtime. The Solution: Shareable Links: Generate a secure URL for instant VM access: no Azure credentials, no VPN, no account creation is required. Implementation: Step 1: Enable Shareable Links Navigate to Bastion → Configuration → Toggle Shareable Link to Enabled → Click Apply Step 2: Generate Link Go to Bastion → Select Shareable Links → Add → Choose VM→ Apply →Copy generated URL Step 3: Share & Monitor Share URL securely with vendor → Vendor connects via browser using VM credentials Monitor active sessions in Bastion → Shareable Links Real World Impact: A global financial services firm now grants emergency vendor access in under 5 minutes instead of 2-3 hours, with zero IT overhead for account provisioning or VPN setup. Links can be revoked after the set duration, eliminating lingering access risks. Every vendor session is logged, providing complete audit trails that satisfy SOX and PCI-DSS compliance requirements without additional administrative effort. Scenario 2: Comprehensive Compliance with Session Recording The Challenge: Your healthcare organization operates under HIPAA regulations, which mandate comprehensive audit trails of all administrative access to systems containing Protected Health Information (PHI). Traditional text logs capture what was accessed, but not what actions were performed—and they're difficult to analyze during audits. You need indisputable video evidence of administrative activities with secure 7-year retention. The Solution: Graphical Session Recording: Azure Bastion Premium's Session Recording feature automatically captures every RDP and SSH session as a video recording, stored securely in Azure Storage with immutable retention policies. Implementation: Step 1: Prepare Storage Account Create a dedicated storage account with blob versioning, lifecycle management (7 years for HIPAA), soft delete (90 days), and RBAC restricted to security/compliance team. Also make sure there is a dedicated container created for Bastion Sessions and CORS policy configured on the storage account to allow your bastion. Step 2: Enable Session Recording Navigate to Bastion → Configuration → Toggle Session Recording to Enabled → Apply Add/Update the SAS URL of the storage account in the Session Recordings blade of Bastion for the recordings to be stored in the specified storage account. Step 3: Connect as Usual Administrators connect through Azure portal normally: VM → Connect → Bastion → Enter credentials → Connect Every session is automatically recorded—no extra steps for users. Step 4: Review Recordings Security teams access recordings from the Session Recordings blade on Azure Bastion which will retrieve data from the configured Storage Account. Real World Impact: A healthcare provider with 50+ hospitals now maintains 100% HIPAA-compliant audit trails of all administrative access to PHI systems through automated video recordings. The organization reduced audit preparation time by 75%, as compliance teams can quickly review specific sessions instead of analyzing thousands of text log entries. Session recordings have enabled post-incident investigations to identify unauthorized configuration changes and provide indisputable video evidence for security reviews and regulatory audits. Scenario 3: Zero Internet Exposure with Private-Only Deployment The Challenge: A global pharmaceutical company developing cancer treatments operates under FDA regulations requiring zero internet exposure for drug development systems. Their security mandate: no public IP addresses on production infrastructure, complete air-gapped connectivity to protect intellectual property, and administrative access from corporate network only. Traditional Azure Bastion requires a public IP address—violating their zero-trust security policy. The Solution: Private-Only Bastion: Azure Bastion Premium's private-only deployment eliminates the public IP address entirely. All connectivity flows through your org’s configured Express Route, S2S or P2S connectivity for complete air-gapped operations. Implementation: Select Azure Bastion Premium SKU and Deploy Private-Only Bastion Configure Private Connectivity from On Prem using your orgs preferred way of connectivity Connect from Corporate Network using Private IP address of the Bastion Deployment Real-World Impact A pharmaceutical company with 20+ research facilities deploys private-only Bastion for FDA-regulated drug development systems. The company now achieves complete air-gapped operations with zero internet endpoints while maintaining centralized access management for 200+ researchers across global facilities. Research teams connect securely via ExpressRoute with all administrative sessions network-isolated, FDA compliance audits confirm 100% of connections originate from corporate private networks, and the organization eliminated $2M in annual costs by decommissioning internet-isolated jump boxes. Conclusion: Azure Bastion transforms the traditional trade-off between security and operational efficiency into a unified solution. Whether you're granting emergency access or preparing for your next HIPAA audit, Azure Bastion delivers what enterprises need: secure temporary access as and when needed, complete audit trails with zero administrator overhead, and comprehensive compliance without compromising productivity, bringing a fundamental shift in how organizations approach secure remote access in the cloud. Resources: https://learn.microsoft.com/azure/bastion/ https://learn.microsoft.com/azure/bastion/shareable-link https://learn.microsoft.com/azure/bastion/session-recording https://azure.microsoft.com/pricing/details/azure-bastion/
Navigating the 2025 holiday season: Insights into Azure’s DDoS defense
The holiday season continues to be one of the most demanding periods for online businesses. Traffic surges, higher transaction volumes, and user expectations for seamless digital experiences all converge, making reliability a non-negotiable requirement. For attackers, this same period presents an opportunity: even brief instability can translate into lost revenue, operational disruption, and reputational impact. This year, the most notable shift wasn’t simply the size of attacks, but how they were executed. We observed a rise in burst‑style DDoS events, fast-ramping, high-intensity surges distributed across multiple resources, designed to overwhelm packet processing and connection-handling layers before traditional bandwidth metrics show signs of strain. From November 15, 2025 through January 5, 2026, Azure DDoS Protection helped customers maintain continuity through sustained Layer 3 and Layer 4 attack traffic, underscoring two persistent realities: Most attacks remain short, automated, and frequently create constant background attack traffic. The upper limit of attacker capability continues to grow, with botnets across the industry regularly demonstrating multi‑Tbps scale. The holiday season once again reinforced that DDoS resilience must be treated as a continuous operational discipline. Rising volume and intensity Between November 15 and January 5, Azure mitigated approximately 174,054 inbound DDoS attacks. While many were small and frequent, the distribution revealed the real shift: 16% exceeded 1M packets per second (pps). ~3% surpassed 10M pps, up significantly from 0.2% last year. Even when individual events are modest, the cumulative impact of sustained attack traffic can be operationally draining—consuming on-call cycles, increasing autoscale and egress costs, and creating intermittent instability that can provide cover for more targeted activity. Operational takeaway: Treat DDoS mitigation as an always-on requirement. Ensure protection is enabled across all internet-facing entry points, align alerting to packet rate trends, and maintain clear triage workflows. What the TCP/UDP mix is telling us this season TCP did what it usually does during peak season: it carried the fight. TCP floods made up ~72% of activity, and ACK floods dominated (58.7%) a reliable way to grind down packet processing and connection handling. UDP was ~24%, showing up as sharp, high-intensity bursts; amplification (like NTP) appeared, but it wasn’t the main play. Put together, it’s a familiar one-two punch: sustain TCP/ACK pressure to exhaust the edge, then spike UDP to jolt stability and steal attention. The goal isn’t just to saturate bandwidth, it’s to push services into intermittent instability, where things technically stay online but feel broken to users. TCP-heavy pressure: Make sure your edge and backends can absorb a surge in connections without falling over—check load balancer limits, connection/state capacity, and confirm health checks won’t start flapping during traffic spikes. UDP burst patterns: Rely on automated detection and mitigation—these bursts are often over before a human can respond. Reduce exposure: Inventory any internet-facing UDP services and shut down, restrict, or isolate anything you don’t truly need. Attack duration: Attackers continued to favor short-lived bursts designed to outrun manual response, but we also saw a notable shift in “who” felt the impact most. High-sensitivity workloads, especially gaming, experienced some of the highest packet-per-second and bandwidth-driven spikes, often concentrated into bursts lasting from a few minutes to several minutes. Even when these events were brief, the combination of high PPS + high bandwidth can be enough to trigger jitter, session drops, match instability, or rapid scaling churn. Overall, 34% of attacks lasted 5 minutes or less, and 83% ended within 40 minutes, reinforcing the same lesson: modern DDoS patterns are optimized for speed and disruption, not longevity. For latency- and session-sensitive services, “only a few minutes” can still be a full outage experience. Attack duration is an attacker advantage when defenses rely on humans to notice, diagnose, and react. Design for minute-long spikes: assume attacks will be short, sharp, and high PPS such that your protections should engage automatically. Watch the right signals: alert on PPS spikes and service health (disconnect rates, latency/jitter), not bandwidth alone. Botnet-driven surges: Azure observed rapid rotation of botnet traffic associated with Aisuru and KimWolf targeting public-facing endpoints. The traffic was highly distributed across regions and networks. In several instances, when activity was mitigated in one region, similar traffic shifted to alternate regions or segments shortly afterward. “Relocation” behavior is the operational signature of automated botnet playbooks: probe → hit → shift → retry. If defenses vary by region or endpoint, attackers will find the weakest link quickly. Customers should standardize protection posture, ensure consistent DDoS policies and thresholds across regions. Monitor by setting the right alerts and notifications. The snapshot below captures the Source-side distribution at that moment, showing which industry verticals were used to generate the botnet traffic during the observation window The geography indicators below reflect where the traffic was observed egressing onto the internet, and do not imply attribution or intent by any provider or country. Preparing for 2026 As organizations transition into 2026, the lessons from the 2025 holiday season marked by persistent and evolving DDoS threats, including the rise of DDoS-for-hire services, massive botnets underscore the critical need for proactive, resilient cybersecurity. Azure's proven ability to automatically detect, mitigate, and withstand advanced attacks (such as record-breaking volumetric incidents) highlights the value of always-on protections to maintain business continuity and safeguard digital services during peak demand periods. Adopting a Zero Trust approach is essential in this landscape, as it operates on the principle of "never trust, always verify," assuming breaches are inevitable and requiring continuous validation of access and traffic principles that complement DDoS defenses by limiting lateral movement and exposure even under attack. To achieve comprehensive protection, implement layered security: deploy Azure DDoS Protection for network-layer (Layers 3 and 4) volumetric mitigation with always-on monitoring, adaptive tuning, telemetry, and alerting; combine it with Azure Web Application Firewall (WAF) to defend the application layer (Layer 7) against sophisticated techniques like HTTP floods; and integrate Azure Firewall for additional network perimeter controls. Key preparatory steps include identifying public-facing exposure points, establishing normal traffic baselines, conducting regular DDoS simulations, configuring alerts for active mitigations, forming a dedicated response team, and enabling expert support like the DDoS Rapid Response (DRR) team when needed. By prioritizing these multi-layered defenses and a well-practiced response plan, organizations can significantly enhance resilience against the evolving DDoS landscape in 2026.A Practical Guide to Azure DDoS Protection Cost Optimization
Introduction Azure provides infrastructure-level DDoS protection by default to protect Azure’s own platform and services. However, this protection does not extend to customer workloads or non-Microsoft managed resources like Application Gateway, Azure Firewall, or virtual machines with public IPs. To protect these resources, Azure offers enhanced DDoS protection capabilities (Network Protection and IP Protection) that customers can apply based on workload exposure and business requirements. As environments scale, it’s important to ensure these capabilities are applied deliberately and aligned with actual risk. For more details on how Azure DDoS protection works, see Understanding Azure DDoS Protection: A Closer Look. Why Cost Optimization Matters Cost inefficiencies related to Azure DDoS Protection typically emerge as environments scale: New public IPs are introduced Virtual networks evolve Workloads change ownership Protection scope grows without clear alignment to workload exposure The goal here is deliberate, consistent application of enhanced protection matched to real risk rather than historical defaults. Scoping Enhanced Protection Customer workloads with public IPs require enhanced DDoS protection to be protected against targeted attacks. Enhanced DDoS protection provides: Advanced mitigation capabilities Detailed telemetry and attack insights Mitigation tuned to specific traffic patterns Dedicated support for customer workloads When to apply enhanced protection: Workload Type Enhanced Protection Recommended? Internet-facing production apps with direct customer impact Yes Business-critical systems with compliance requirements Yes Internal-only workloads behind private endpoints Typically not needed Development/test environments Evaluate based on exposure Best Practice: Regularly review public IP exposure and workload criticality to ensure enhanced protection aligns with current needs. Understanding Azure DDoS Protection SKUs Azure offers two ways to apply enhanced DDoS protection: DDoS Network Protection and DDoS IP Protection. Both provide DDoS protection for customer workloads. Comparison Table Feature DDoS Network Protection DDoS IP Protection Scope Virtual network level Individual public IP Pricing model Fixed base + overage per IP Per protected IP Included IPs 100 public IPs N/A DDoS Rapid Response (DRR) Included Not available Cost protection guarantee Included Not available WAF discount Included Not available Best for Production environments with many public IPs Selective protection for specific endpoints Management Centralized Granular Cost efficiency Lower per-IP cost at scale (100+ IPs) Lower total cost for few IPs (< 15) DDoS Network Protection DDoS Network Protection can be applied in two ways: VNet-level protection: Associate a DDoS Protection Plan with virtual networks, and all public IPs within those VNets receive enhanced protection Selective IP linking: Link specific public IPs directly to a DDoS Protection Plan without enabling protection for the entire VNet This flexibility allows you to protect entire production VNets while also selectively adding individual IPs from other environments to the same plan. For more details on selective IP linking, see Optimizing DDoS Protection Costs: Adding IPs to Existing DDoS Protection Plans. Ideal for: - Production environments with multiple internet-facing workloads - Mixed environments where some VNets need full coverage and others need selective protection - Scenarios requiring centralized visibility, management, and access to DRR, cost protection, and WAF discounts DDoS IP Protection DDoS IP Protection allows enhanced protection to be applied directly to individual public IPs, with per-IP billing. This is a standalone option that does not require a DDoS Protection Plan. Ideal for: Environments with fewer than 15 IPs requiring protection Cases where DRR, cost protection, and WAF discounts are not needed Quick enablement without creating a protection plan Decision Tree: Choosing the Right SKU Now that you know the main scenarios, the decision tree below can help you determine which SKU best fits your environment based on feature requirements and scale: Network Protection exclusive features: DDoS Rapid Response (DRR): Access to Microsoft DDoS experts during active attacks Cost protection: Resource credits for scale-out costs incurred during attacks WAF discount: Reduced pricing on Azure Web Application Firewall Consolidating Protection Plans at Tenant Level A single DDoS Protection Plan can protect multiple virtual networks and subscriptions within a tenant. Each plan includes: Fixed monthly base cost 100 public IPs included Overage charges for additional IPs beyond the included threshold Cost Comparison Example Consider a customer with 130 public IPs requiring enhanced protection: Configuration Plans Base Cost Overage Total Monthly Cost Two separate plans 2 $2,944 × 2 = $5,888 $0 ~$5,888 Single consolidated plan 1 $2,944 30 IPs × $30 = $900 ~$3,844 Savings: ~$2,044/month ($24,528/year) by consolidating to a single plan. In both cases, the same public IPs receive the same enhanced protection. The cost difference is driven entirely by plan architecture. How to Consolidate Plans Use the PowerShell script below to list existing DDoS Protection Plans and associate virtual networks with a consolidated plan. Run this script from Azure Cloud Shell or a local PowerShell session with the [Az module](https://learn.microsoft.com/powershell/azure/install-azure-powershell) installed. The account running the script must have Network Contributor role (or equivalent) on the virtual networks being modified and Reader access to the DDoS Protection Plan. # List all DDoS Protection Plans in your tenant Get-AzDdosProtectionPlan | Select-Object Name, ResourceGroupName, Id # Associate a virtual network with an existing DDoS Protection Plan $ddosPlan = Get-AzDdosProtectionPlan -Name "ConsolidatedDDoSPlan" -ResourceGroupName "rg-security" $vnet = Get-AzVirtualNetwork -Name "vnet-production" -ResourceGroupName "rg-workloads" $vnet.DdosProtectionPlan = New-Object Microsoft.Azure.Commands.Network.Models.PSResourceId $vnet.DdosProtectionPlan.Id = $ddosPlan.Id $vnet.EnableDdosProtection = $true Set-AzVirtualNetwork -VirtualNetwork $vnet Preventing Protection Drift Protection drift occurs when the resources covered by DDoS protection no longer align with the resources that actually need it. This mismatch can result in wasted spend (protecting resources that are no longer critical) or security gaps (missing protection on newly deployed resources). Common causes include: Applications are retired but protection remains Test environments persist longer than expected Ownership changes without updating protection configuration Quarterly Review Checklist List all public IPs with enhanced protection enabled Verify each protected IP maps to an active, production workload Confirm workload criticality justifies enhanced protection Review ownership tags and update as needed Remove protection from decommissioned or non-critical resources Validate DDoS Protection Plan consolidation opportunities Sample Query: List Protected Public IPs Use the following PowerShell script to identify all public IPs currently receiving DDoS protection in your environment. This helps you audit which resources are protected and spot candidates for removal. Run this from Azure Cloud Shell or a local PowerShell session with the Az module installed. The account must have Reader access to the subscriptions being queried. # List all public IPs with DDoS protection enabled Get-AzPublicIpAddress | Where-Object { $_.DdosSettings.ProtectionMode -eq "Enabled" -or ($_.IpConfiguration -and (Get-AzVirtualNetwork | Where-Object { $_.EnableDdosProtection -eq $true }).Subnets.IpConfigurations.Id -contains $_.IpConfiguration.Id) } | Select-Object Name, ResourceGroupName, IpAddress, @{N='Tags';E={$_.Tag | ConvertTo-Json -Compress}} For a comprehensive assessment of all public IPs and their DDoS protection status across your environment, use the DDoS Protection Assessment Tool. Making Enhanced Protection Costs Observable Ongoing visibility into DDoS Protection costs enables proactive optimization rather than reactive bill shock. When costs are surfaced early, you can spot scope creep before it impacts your budget, attribute spending to specific workloads, and measure whether your optimization efforts are paying off. The following sections cover three key capabilities: budget alerts to notify you when spending exceeds thresholds, Azure Resource Graph queries to analyze protection coverage, and tagging strategies to attribute costs by workload. Setting Up Cost Alerts Navigate to Azure Cost Management + Billing Select Cost alerts > Add Configure: o Scope: Subscription or resource group o Budget amount: Based on expected DDoS Protection spend o Alert threshold: 80%, 100%, 120% o Action group: Email security and finance teams Tagging Strategy for Cost Attribution Apply consistent tags to track DDoS protection costs by workload: # Tag public IPs for cost attribution $pip = Get-AzPublicIpAddress -Name "pip-webapp" -ResourceGroupName "rg-production" $tags = @{ "CostCenter" = "IT-Security" "Workload" = "CustomerPortal" "Environment" = "Production" "DDoSProtectionTier" = "NetworkProtection" } Set-AzPublicIpAddress -PublicIpAddress $pip -Tag $tags Summary This guide covered how to consolidate DDoS Protection Plans to avoid paying multiple base costs, select the appropriate SKU based on IP count and feature needs, apply protection selectively with IP linking, and prevent configuration drift through regular reviews. These practices help ensure you're paying only for the protection your workloads actually need. References Review Azure DDoS Protection pricing Enable DDoS Network Protection for a virtual network Configure DDoS IP Protection Configure Cost Management alertsZero Trust with Azure Firewall, Azure DDoS Protection and Azure WAF: A practical use case
Introduction Zero Trust has emerged as the defining security ethos of the modern enterprise. It is guided by a simple but powerful principle: “Never trust, always verify.” This principle is more relevant now than ever as cyberattacks continue to trend upward in both frequency and impact, affecting organizations of every size and industry. No entity large or small can assume immunity. As a result, adopting Zero Trust is no longer optional, it is a foundational requirement for designing secure, resilient architectures. A key tenet of Zero Trust is the assumption of breach, thus designing systems with the expectation that threats may already exist both outside and inside the network perimeter. To implement this principle, you need multiple, independent security controls that inspect traffic at different layers and enforce least privilege access continuously. Relying on a single security control, even a highly capable one, leaves gaps that modern attackers are adept at exploiting. It is within this context that combining the use of Azure Firewall, Azure DDoS Protection and Azure Web Application Firewall (WAF) services to secure Web Applications while protecting the network perimeter becomes important. Together, these services deliver comprehensive protection across the network and application layers. Defense-in-depth: Why Azure WAF, Azure DDoS Protection and Azure Firewall are essential for Zero Trust In these sections ahead, we examine the common network and application-layer attack vectors that target modern web applications and illustrate how Azure WAF, Azure DDoS protection, and Azure Firewall, when layered strategically, work in tandem to mitigate these threats. The architecture The test environment was designed to reflect a common Azure deployment pattern: Azure DDoS Protection at the edge, to defend against a comprehensive set of network layer (layer 3/4) attacks Azure Application Gateway with WAF, inspecting inbound HTTP traffic for application-layer threats Azure Firewall Premium behind the gateway, providing network-layer protection, deep packet inspection, and outbound traffic governance. A backend subnet hosting an intentionally vulnerable application (OWASP Juice Shop) to simulate real-world attack scenarios. Traffic flows through the DDoS first, then WAF, and then the firewall, before reaching the backend. Outbound traffic from the backend is routed through the firewall for inspection. This ensures that all inbound and outbound traffic is scrutinized. Two access paths that will be tested: Via the Application Gateway public IP, where traffic passes through DDoS, WAF and Firewall. Via the Firewall public IP using a DNAT rule, where traffic bypasses WAF and is inspected only by the Firewall. The following scenarios illustrate how this complementary protection strengthens overall resilience: Scenario 1: SQL injection (application-layer attack) Let’s say an attacker on the internet attempts to access the application’s login endpoint via the Application Gateway IP address and injects a SQL payload into the input field. For example, the attacker submits a request containing the following payload in the User ID field: ?id=' OR 1=1 -- Azure WAF will receive the request, analyze, and if Azure WAF is deployed in Prevention mode, it will immediately detect the SQL injection attempt using its built-in Managed Ruleset. Upon detection, Azure WAF will return a WAF block page, preventing the request from ever reaching the application. By contrast, when the same application is accessed through a firewall-only path (for example, via a DNAT rule on Azure Firewall that exposes the application on port 443), Azure Firewall allows the traffic as it does not perform deep Application layer inspection and SQL injection payloads when embedded within the HTTP request body, appear legitimate at the network layer. Here is a snapshot of the attacker gaining access to the admin role when they insert this SQL injection attack without Azure WAF and only Azure Firewall in the path. Scenario 2: Volumetric and application-layer DDoS attacks Next, the attacker launches a volumetric network layer DDoS (SYN/UDP floods) to saturate bandwidth, but Azure DDoS Network Protection absorbs and scrubs the attack at the edge, so no traffic reaches Application Gateway, WAF, or Firewall. When the network layer attack fails, they shift to HTTP flood attack at the application layer, overwhelming the web application with a high volume of requests. Some requests include exploit attempts, while others are designed purely to exhaust application resources. Azure WAF here, can identify malicious patterns such as: Automated bots lacking proper headers Abnormal request rates Known exploit payloads embedded within requests Malicious IP addresses Note: Azure DDoS Protection is a comprehensive service that provides protection across network layers (Layer 3 and 4), while HTTP DDoS Protection specifically targets application-layer attacks (Layer 7) and is integrated with Azure WAF. They are complementary services designed to defend against different types of threats within the Azure environment. Additionally, if the botnet’s IPs are known threat actors or malicious traffic, Azure Firewall’s threat intelligence and IDPS will be able to flag this traffic too. Together, these services form a complementary, defense-in-depth strategy for protecting Azure workloads against distributed denial-of-service attacks. Scenario 3: Path Traversal Attempt/Information leak: (Application-Layer Attack) Next, the attacker sends HTTP requests to access sensitive system files such as /etc/passwd by sending crafted HTTP requests to the application via the Application Gateway public IP address. The request successfully passes through Azure Application Gateway WAF, as it does not trigger a managed rule violation in this case. However, when the request reaches Azure Firewall, the Firewall’s IDPS detects the malicious pattern in the HTTP header and blocks the connection before it can reach the backend workload. Because the backend connection is denied by Azure Firewall, Application Gateway is unable to establish a successful response and returns a 504 Gateway Timeout to the client, rather than a 403 Forbidden response that would typically be generated by WAF when it blocks traffic. Below is the log from Azure Firewall showing that its able to detect this traffic as – Attempted Information Leak. As seen below, the traffic passed Application Gateway+WAF but was caught by Azure Firewall: This scenario highlights an important architectural outcome: The combination of WAF and Azure Firewall provides layered enforcement, even if an attack manages to slip past Azure WAF, Azure Firewall adds an additional enforcement layer to ensure the application remains protected. Now, let’s look at some more Network Layer attacks: Scenario 4: Network reconnaissance and breach In this scenario, port 3389 is exposed on Application Gateway using the L4 TCP Proxy option. Now, the attacker attempts to scan the Application Gateway on all the ports/protocols and found that port 3389 was open along with other ports such as ports 80, 8080, 3000. Azure WAF will alert us for Layer 7/Application exploit but cannot verify/validate the attack on port 3389 since it was purely Layer 3/4 and contained no HTTP payload for WAF inspection. The L4 proxy listener on App Gateway simply forwards the raw TCP connections to the Azure Firewall behind it. Azure Firewall, however, performs full network‑layer inspection across all ports and protocols, allowing it to detect and alert on this type of L3/L4 reconnaissance even when App Gateway had the port open via the TCP proxy feature. As seen below the traffic passed Application Gateway+WAF but was caught by Azure Firewall since it is non-HTTP: The attacker then tries a different approach: Now the attacker somehow compromises a workstation inside our network and attempts to move laterally to the web server via RDP on port 3389 and/or attempts to exfiltrate and try to access something outside of the network. Azure Firewall located inside the VNet blocks the RDP attempt (if there is no rule allowing it) and if there is, its IDPS flags/blocks the traffic as suspicious. In this case, Azure WAF will not be involved but Azure Firewall inspects this internal and/or outbound traffic and blocks it. This illustrates how a combination of the two stops the attacker at multiple points: firewall foiled the reconnaissance and lateral movement/exfiltration, WAF foiled the application exploit. We can see below the outbound malicious attempt caught by Azure Firewall IDPS: In summary, Azure WAF is like the “bodyguard at the application’s front door” – inspecting every HTTP request in detail and ejecting those carrying hidden weapons or exhibiting bad behavior. It focuses on the web layer, which Azure Firewall or DDoS alone cannot fully protect. If we only had the WAF and no network firewall or DDoS, we’d be safe from many web attacks but would remain exposed to network-level threats (e.g., someone trying to RDP into a VM, or flooding a non-HTTP service). Conversely, if we had only the firewall, a crafty attacker could still exploit a vulnerability in our web app with a well-crafted HTTP request that looks “allowed” to the firewall – that’s where the WAF comes in to catch it. Azure Firewall on the other hand, acts as the “moat and drawbridge” to your cloud network: it keeps out the obvious bad guys at the gate, tightly limits what’s allowed in or out (no implicit trust for internal IPs), and uses threat intel + signatures to sniff out known threats in any traffic it passes, even outbound traffic. The table below shows the traffic flow that will be filtered by Azure WAF vs Azure Firewall. As you can see, layered security is fundamental to Zero Trust Conclusion In a Zero Trust architecture, security cannot rely on implicit trust or a single layer of defense. The combination of Azure Firewall Premium, Azure DDoS protection and Azure Application Gateway WAF exemplifies defense-in-depth by protecting both network and application layers. Organizations hosting internet-facing applications should adopt this layered strategy to reduce exposure to modern threats, prevent lateral movement, and maintain strict control over outbound traffic. By implementing these services together, you align with Microsoft’s recommended best practices for Zero Trust and significantly strengthen your cloud security posture. References: Implement a Zero Trust network for web applications by using Azure Firewall and Azure Application Gateway What is Azure Web Application Firewall? Azure DDoS Protection Overview | Microsoft Learn What is Azure Firewall? Architecture designs using Azure WAF and Azure Firewall together Zero Trust Assessment Overview | Microsoft LearnApplication layer DDoS protection using the HTTP DDoS Ruleset in Azure WAF
Today, Distributed Denial of Service (DDoS) attacks can strike as soon as public connectivity is enabled, highlighting their widespread prevalence. Factors such as easily accessible botnets, the explosion of IoT devices, and the growth of API-driven workloads, e-commerce platforms, and global web applications have made these attacks easier to launch and more impactful. Importantly, attackers are no longer focusing solely on the network layer, they increasingly target the application layer. Application-layer DDoS attacks often mimic normal user activity, making detection and mitigation far more challenging than traditional network-layer attacks. The most common types of Application layer/HTTP based DDOS attacks are outlined below. Common HTTP-based DDoS attacks: HTTP floods: Large volumes of valid looking GET or POST requests are sent to webpages or APIs, overwhelming application gateways and backend services without saturating network bandwidth. API abuse attacks: Attackers repeatedly call specific API endpoints, such as authentication, search, or checkout that trigger expensive backend operations, quickly exhausting compute and database resources. Slow HTTP attacks: Connections are deliberately kept open by sending data very slowly, consuming server threads and connection limits while generating relatively little traffic. TLS-intensive attacks: A high number of encrypted connections are initiated to increase CPU usage during TLS handshakes, impacting application gateways and load balancers. In order to defend against these sophisticated threats, organizations need application-aware protection that can identify abnormal behavior patterns rather than relying only on traffic volume. This is precisely the capability provided by the HTTP DDoS Ruleset for Azure Application Gateway WAF. What Is the HTTP DDoS Ruleset? The HTTP DDoS Ruleset is a built-in capability of Azure Application Gateway WAF designed to protect your applications from large-scale HTTP floods at the application layer. Unlike static rate-limiting or manual IP blocking, this ruleset uses adaptive learning to understand what “normal” traffic looks like for your gateway and then automatically mitigates anomalies. Key features Baseline learning: The ruleset observes traffic for about 24 hours to establish a normal request pattern per gateway. Dynamic detection: When incoming requests exceed the learned baseline, the ruleset identifies potential abuse (Client-specific or IP specific limits are applied only when the overall request volume to the gateway exceeds its learned baseline). Automated mitigation: Offending clients are blocked and are placed in a “penalty box” for the defined time (15 minutes). Sensitivity levels: Choose low, medium, or high to control aggressiveness. Medium is recommended for most workloads. Leverages Microsoft’s vast global network’s threat intelligence to establish a stricter baseline for suspected botnet traffic and when exceeded, blocks them and places those suspected bots into the penalty box. Threat intelligence plays a critical role here. By continuously aggregating data from global telemetry, threat intelligence systems can identify sources that are likely participating in coordinated attacks. When applied to HTTP DDoS protection, this intelligence allows suspected bot traffic to be treated differently from normal user traffic. Instead of relying only on static blocklists, botnet-aware defenses use reputation, behavior, and historical signals to apply throttling or penalties dynamically. This approach reduces the attack surface, limits the impact of distributed bot-driven floods, and avoids unnecessary disruption to legitimate users. Threat intelligence shifts DDoS defense from a purely reactive posture to a more informed, proactive one, making it far more effective against today’s botnet-driven application-layer attacks. Enabling and validating the HTTP DDoS Ruleset: Getting started with the HTTP DDoS Ruleset on Application Gateway WAF is simple. Enable the Ruleset: In the Azure portal, open your WAF policy. Note: Currently the ruleset is available only in the preview portal: https://preview.portal.azure.com/ Under Managed Rules, Click on Assign and then assign the HTTP DDoS Ruleset_1.0 (Preview) and save. Each rule can be configured to either Log traffic for observation or Deny traffic for active mitigation. Sensitivity can be adjusted to High, Medium, or Low, allowing you to balance detection speed and accuracy. Higher sensitivity enforces lower thresholds and detects anomalies sooner, while lower sensitivity raises thresholds to reduce false positives. Medium sensitivity is the default and recommended setting for most workloads. Once enabled, the ruleset is evaluated early in the WAF pipeline, before custom rules are processed. This ensures that HTTP-based DDoS protection cannot be bypassed by DDoS protection. The ruleset works alongside the Default Rule Set (DRS) and any custom rules for comprehensive security. After the policy is applied to an Application Gateway, the ruleset enters a learning phase that lasts at least 24 hours. During this time, it observes traffic patterns to establish normal baselines for the gateway. No detection or blocking occurs during this period, allowing the ruleset to understand typical application behavior before enforcement begins. Metrics: Once the learning phase completes, traffic surges that exceed the learned baseline are reflected in the Application Gateway metrics. These metrics provide immediate visibility into when the HTTP DDoS ruleset is actively detecting and mitigating abnormal behavior. Metric – WAF Penalty Box Size This metric shows how many IP addresses are currently inside the penalty box, meaning that the WAF has detected them exceeding the learned HTTP DDoS baseline and is temporarily blocking them. A spike here indicates that multiple clients crossed their thresholds at the same time, often during an attack or load-test scenario. Metric – WAF Penalty Box Hits This metric represents how many IPs entered the penalty box. Every time a client breaches its threshold, the ruleset logs a hit and places that IP into the penalty box for approximately 15 minutes. Multiple hits often correlate with repeated spikes or sustained abusive traffic patterns. Logs: For deeper analysis, enabling diagnostic settings allows you to inspect HTTP DDoS Ruleset events directly in the logs. These logs provide granular details about which IPs were flagged, why they were flagged, and how far they exceeded expected thresholds. Example of DetailedData from a log: RemoteAddress: 4.x.x.x (Public IP) crossed threshold. Expected: 4400.000000 request per 900 seconds, Actual: 8407.000000 requests per 900 seconds. KQL queries to retrieve these logs: Resource specific logs: AGWFirewallLogs | where RuleSetType == "Microsoft_HTTPDDoSRuleSet" Diagnostic logs: AzureDiagnostics | where Category == "ApplicationGatewayFirewallLog" | where ruleSetType_s == "Microsoft_HTTPDDoSRuleSet" Note: Identify IPs repeatedly flagged and confirm they’re malicious, not legitimate clients. Conclusion: The threat landscape continues to evolve, and defenses must evolve with it. Leveraging the HTTP DDoS Ruleset in Azure Application Gateway WAF helps ensure protections keep pace with modern application-layer attacks. With built-in visibility through metrics and logs, teams can better understand traffic behavior and operate their WAF with greater confidence. Next Steps: Access the HTTP DDoS ruleset for Application Gateway via the preview portal: https://preview.portal.azure.com/ HTTP DDoS Ruleset (Preview) - Application Gateway WAF | Microsoft Learn Azure Web Application Firewall (WAF) policy overview | Microsoft Learn
