July 29, 2026: We’ve updated this post to clarify the AWS Firewall Manager migration path.

Application-layer distributed denial of service (DDoS) attacks are difficult to detect because they closely resemble legitimate traffic. HTTP request floods are now among the most common vectors targeting web applications, using valid-looking requests that blend in with normal user activity.

In June 2025, AWS launched the AWS WAF Anti-DDoS managed rule group, built specifically for application-layer (L7) DDoS protection. AWS Shield Advanced is adopting it as the default application-layer protection, and in time as the only one. On July 27, AWS Shield Advanced begins adding the Anti-DDoS managed rule group to eligible web access control lists (ACLs) in Count mode. It will not cause any interruption to your traffic alongside your existing L7 automatic mitigation and WAF rules. In this blog post, we provide details regarding the Anti-DDoS managed rule group and when the change is expected to reach your web ACLs. You will understand the phases and steps that you need to take before the finish date, including how the monitoring and metrics will change.

The Anti-DDoS managed rule group builds on what Shield Advanced automatic mitigation already provides. It profiles your traffic, learns what normal traffic looks like for your application, and establishes a baseline in minutes rather than hours. When an attack starts, it reacts within seconds and there are no health checks to configure. The rule group adds a Challenge action to the Block and Count actions you already use. Challenge decisions are driven by the AMR labels that mark the suspicion level of each inspected request. One option is a silent browser challenge, which has a background verification that runs in the visitor’s browser with no interstitial page, so legitimate users are never interrupted while automated traffic is filtered out. You can also exclude workload paths that don’t support Challenge, which fall back to Block mitigations instead. Sensitivity is configurable to Low, Medium, or High, and you set it separately for Block and Challenge. Block and Challenge are tuned independently; meaning you can run Challenge at high sensitivity to catch more suspicious traffic while keeping Block low to avoid dropping legitimate requests or reverse it for a stricter posture.

The rest is about cost and visibility:

• It uses less capacity than before. The rule group needs 50 web ACL capacity units (WCUs), down from the 150 the previous protection required, providing you with capacity for the rest of your rules.
• The dashboard ships in the AWS Management Console for AWS WAF. It’s there now, showing live DDoS events, match metrics, and the top URIs, geographies, and IP addresses driving traffic.
• It labels everything it inspects. Requests get labels for event-detected, graduated suspicion levels, and specific rules. Match on those labels in your own AWS WAF rules when you need logic the rule group doesn’t cover.
• You don’t pay for the attack traffic. During active mitigation, blocked DDoS requests drop out of your monthly count. That exclusion covers AWS WAF request fees, Anti-DDoS managed rule group request fees, and Shield Advanced request charges.

AWS Shield Advanced isn’t required to use any of these features. Shield Advanced subscribers get the rule group included with AWS WAF and any customer can turn it on independently. See AWS WAF pricing for more information on costs.

Shield Advanced upgrades application-layer DDoS protection in five phases. The following dates are when AWS will act automatically, not the earliest date when you can act. After the rule group is deployed in Count mode on July 27, 2026, you can begin migrating right away rather than waiting for the October auto-upgrade. There’s no window where protection lapses. Your current automatic mitigation stays active through every phase until the Anti-DDoS managed rule group takes over. That handoff happens in a single operation, with no cutover window and no gap for your traffic flows.

AWS adds the Anti-DDoS managed rule group in Count mode to every web ACL eligible for this rollout. Eligible means any Shield Advanced web ACL with at least one resource using application-layer automatic mitigation that isn’t already running the Anti-DDoS rule group. This is a broader set than the web ACLs eligible for the October auto-upgrade (Phase 3), which applies a stricter test. The deployment rolls out gradually, starting July 27 and expected to finish by August 7, 2026, so different web ACLs might be updated on different days. There’s no impact to your traffic because the rule group watches and labels requests without acting on them while your existing automatic mitigation keeps running. Throughout the evaluation period, you receive DDoS events, metrics, and AWS WAF labels at no additional charge.

The existing automatic mitigation and the Anti-DDoS managed rule group run side by side each detecting independently. Automatic mitigation continues to protect your resources while the rule group operates in Count mode. To compare their detection results, use the DDoSAttackRequests metric, AWS WAF labels, and the Anti-DDoS dashboard. All Anti-DDoS managed rule group charges are waived during this period, including the subscription fee, per-request fees, and WCU consumption costs for the eligible web ACLs from phase 1.

For eligible web ACLs, the auto-upgrade mirrors your existing automatic mitigation configuration. The rule group inherits your current setting, so a Block configuration comes up in Block mode and a Count configuration comes up in Count mode in a single, atomic operation. The rule group takes over in the same step that disables automatic mitigation, so protection never drops for an instant. This is a handoff rather than a cutover with no window where your resources are unprotected. If you’d rather not upgrade you can opt out by contacting AWS Support before the auto-upgrade date.

You don’t have to wait for the October auto-upgrade to migrate. As soon as the rule group is deployed in Count mode between July 27 and August 7, 2026, you can move to it on your own schedule. This is the path to use for web ACLs that aren’t eligible for the Phase 3 auto-upgrade, meaning mixed-mode web ACLs or ones with resources that don’t have automatic mitigation enabled. Work with your AWS account team and AWS Support at any point in this window to plan and complete the migration. Eligible web ACLs are also upgraded automatically starting October 1 (Phase 3), so guided migration is mainly for the web ACLs the auto-upgrade can’t cover.

As of January 1, 2027, the Shield Advanced application-layer automatic mitigation feature will no longer be available. Resources that haven’t migrated to the Anti-DDoS managed rule group will lose automatic application-layer DDoS mitigation.

The existing automatic mitigation and the Anti-DDoS managed rule group use separate Amazon CloudWatch namespaces and metric structures. The rule group gives you three tiers of observability: tier 1 tells you an attack is happening, tier 2 shows which requests it flagged and why, and tier 3 shows what it did about them. You don’t need all three on day 1 because most customer teams start at tier 1 to confirm detection is working, then add the others as they tune.

You can detect DDoS events using two CloudWatch metrics, each with its own namespace.

What this means for your existing alarms:

• After the application-layer automatic mitigation feature is sunset, DDoSDetected still fires for infrastructure layer 3 and layer 4 events, so your existing network layer and transport layer alarms remain valid. For the full list, see AWS Shield Advanced metrics.
• DDoSAttackRequests is the Anti-DDoS managed rule group equivalent for application-layer event detection. Alarm on Sum >= 1 to detect any event, or set a volume threshold (for example, more than 10,000 requests per minute) for severity-based alerting.
• During the evaluation period, both metrics fire independently and you can validate detection parity before migrating your application-layer alarms.
• Because DDoSAttackRequests is absent when there are no active DDoS events, set treat-missing-data to missing or notBreaching for alarms on this metric.

Every request the Anti-DDoS managed rule group evaluates gets a label. Where tier 1 tells you an attack started, tier 2 shows which requests looked suspicious and how confident the rule group was. The labels surface as AWS WAF metrics in the AWS/WAFV2 namespace: AllowedRequests, BlockedRequests, and CountRuleMatch. Each carries the LabelName and LabelNamespace dimensions under the awswaf:managed:aws:anti-ddos: namespace.

• event-detected – Requests observed during a detected DDoS event
• ddos-request – Requests identified as part of the attack
• low-suspicion-ddos-request, medium-suspicion-ddos-request, high-suspicion-ddos-request – Graduated suspicion levels
• challengeable-request – Requests eligible for browser challenge

Chart suspicion-level trends on a CloudWatch dashboard to see how an attack builds. Match on the labels in your own AWS WAF rules or dig into them in your AWS WAF logs with CloudWatch Logs Insights or Amazon Athena when you need to understand a specific event after the fact.

Where tier 2 shows what the rule group flagged, tier 3 shows what it did about those requests during an event. You’ll find these metrics as ChallengeRequests, BlockedRequests, and CountRuleMatch, each scoped by the rule label that produced it.

• ChallengeAllDuringEvent – Requests challenged during an active event
• ChallengeDDoSRequests – Suspected DDoS requests challenged based on suspicion level
• DDoSRequests – Requests blocked (or counted in Count mode)

Watch these during a live event to see whether mitigation is keeping up. If you’re challenging far more requests than you’re blocking, your configuration might be too cautious, and you can raise the sensitivity level after you trust the numbers.

Your Shield Advanced subscription includes the Anti-DDoS managed rule group for up to 50 billion requests per month, counted across your whole organization at the payer account level. For most customers that ceiling is well above normal traffic, so you won’t see a line item here unless you’re operating at very high volume. For the exact rates, see AWS WAF pricing and Shield Advanced pricing.

You aren’t charged for DDoS traffic while the Anti-DDoS managed rule group is actively mitigating, which means Block or Challenge mode rather than Count. This applies to AWS WAF request fees, Anti-DDoS managed rule group request fees, and Shield Advanced request charges. Leaving the rule group in Count mode past the evaluation period costs you the protection without the billing relief, so avoid staying in Count mode longer than you need to validate.

During the evaluation period (July 27 to September 30, 2026), the eligible web ACLs AWS auto-enrolled don’t incur per-request fees or WCU consumption, even when configured in Count mode.

The Anti-DDoS managed rule group works at the web ACL level, so every resource you associate with a web ACL shares that coverage. Before assuming a single resource accounts for the whole cost, look at how many resources sit behind each web ACL. A web ACL fronting 20 resources bills differently from one fronting 2, so check that count first and familiarize yourself with the workload protected by each web ACL.

Adding the Anti-DDoS managed rule group to a web ACL yourself isn’t part of the upgrade path, so standard pricing applies from the moment you enable it. The same is true for any resource that was already running the rule group before the rollout. To get the free evaluation, let the automatic rollout reach your web ACLs rather than adding the rule group ahead of it. There’s no penalty for adding it yourself; you just don’t receive the waiver on that web ACL.

If you manage web ACLs with AWS CloudFormation, AWS Cloud Development Kit (AWS CDK), Terraform, or other infrastructure as code (IaC), the auto-upgrade changes your infrastructure configuration outside your templates. Your code is still the source of truth, so you need to do two things. First, change where the protection is declared. Today you enable application-layer automatic mitigation through the Shield API (EnableApplicationLayerAutomaticResponse), configured per protected resource. The Anti-DDoS managed rule group is configured through the AWS WAF API instead (CreateWebACL and UpdateWebACL), as a managed rule group statement inside the web ACL, scoped per web ACL rather than per resource. In IaC terms, you remove the Shield automatic-response block (for example, Terraform’s aws_shield_application_layer_automatic_response) and add the WAF managed rule group statement shown in the following section. Second, pull the upgraded web ACL back into your tooling before your next deploy, or your pipeline will try to revert the change.

For the full statement in Terraform, CloudFormation, and the AWS CDK, plus how to sync state after the auto-upgrade (terraform plan, CloudFormation drift detection, cdk diff), see the iac-webacl-examples helper.

If you’re currently running a Shield Advanced policy in AWS Firewall Manager, check its Automatic application layer DDoS mitigation setting before you start, because that setting decides how much of this section applies to you. Where it reads Ignore or Disable, the policy isn’t managing that mitigation at all: whatever mitigation your resources have was enabled on the resources themselves, or through Shield, and that’s where you turn it off when the time comes.

If the Shield Advanced policy reads Enable, you first need to add or reuse an AWS WAF Firewall Manager policy, put the Anti-DDoS managed rule group in it and scope that policy to the same accounts and resources your Shield Advanced policy covers.

Keep the Shield Advanced policy in place throughout the process. Don’t remove accounts or resources from its scope, and don’t delete it. Firewall Manager revokes the Shield Advanced protections it created for anything that leaves scope, which ends L3 and L4 coverage, along with the application-layer mitigation you’re replacing. Instead, use a setting change to retire the older mitigation: when the new rule group is live and you’ve compared the two, set Automatic application layer DDoS mitigation to Disable on the Shield Advanced policy that currently reads Enable.

Set up the AWS WAF Firewall Manager policy

You can make this change in the console or as code. If you manage your Firewall Manager policies as code, don’t edit them in the console: add a new AWS WAF policy or update an existing one in your templates with the Anti-DDoS managed rule group included, and deploy it using the following Firewall Manager policies using IaC steps. Otherwise, use the console.

In the console, follow Creating an AWS Firewall Manager policy for AWS WAF to create the policy and reach the Edit policy rules page. Add the Anti-DDoS rule group, listed there as AWS AntiDDoS Protection for Layer 7 attacks (AWSManagedRulesAntiDDoSRuleSet), as a new rule group under First rule groups so it evaluates before your other managed groups, but below any Allow custom rules you use to fast-path known-good traffic.

If you protect CloudFront distributions, make this change in your Global policy, and repeat it in each AWS Regional policy for regional resources. Save the policy, and Firewall Manager rolls the change out to in-scope accounts, which can take a few minutes.

After being added, the rule group appears as the first rule group in the policy, as shown in the following screenshot:

Figure 1: AntiDDoS enabled

If you manage Firewall Manager policies as code, make the change in your template instead of the console. The Anti-DDoS managed rule group goes into the AWS WAF policy’s ManagedServiceData, a WAFV2 policy definition carried as a JSON string, added to the first rule groups so it evaluates early. For the ManagedServiceData JSON with CloudFormation, Terraform, and AWS CDK examples, see the firewall-manager-examples helper.

Whichever path you take, scope the policy to the same accounts and resources your Shield Advanced policy already covers, so no resource loses application-layer protection during the move.

Between July 27 and August 7, 2026, AWS will add the Anti-DDoS managed rule group in Count mode to Shield Advanced web ACLs that have resources using application layer automatic mitigation but not yet the Anti-DDoS rule group. After it reaches your web ACL, you can evaluate it, and migrate whenever you’re ready, without waiting for the October auto-upgrade.

• Review the Anti-DDoS dashboard in the AWS WAF console. The dashboard shows real-time DDoS events, match metrics, and top traffic sources.
• Compare event detection side by side. During Count mode, both systems detect independently. Check the DDoSDetected metric in AWS/DDoSProtection alongside DDoSAttackRequests in AWS/WAFV2 to validate detection parity for your resources. You can deploy the CloudWatch comparison dashboard from the AWS Samples repository to view both systems on a single dashboard.
• Explore AWS WAF labels. Enable AWS WAF logging and query for labels in the awswaf:managed:aws:anti-ddos: namespace. Look at suspicion levels (low-suspicion-ddos-request, medium-suspicion-ddos-request, high-suspicion-ddos-request), event-detected, and challengeable-request to see per-request visibility into detected events.
• Start with Low sensitivity for Block actions during evaluation to minimize false positive risk. Tune up as you gain confidence from the Anti-DDoS dashboard and AWS WAF label data.
• Plan your configuration. Review sensitivity levels, URI exemptions for non-HTML paths, and web ACL priority placement. The Anti-DDoS managed rule group should run at the highest priority in your web ACL, or right below any custom rules with the Allow action.
• Sync your IaC templates. After the auto-upgrade adds the Anti-DDoS managed rule group to your web ACL, fetch the current state into your IaC tooling (Terraform refresh, CloudFormation drift detection, AWS CDK import) before your next deployment.

The Anti-DDoS managed rule group profiles your traffic within minutes and mitigates within seconds, where the automatic mitigation it builds on established its baseline over hours, and it gives you granular visibility into what it’s doing. The evaluation period exists so you can watch both systems run on your own traffic before anything changes. Spend the first few weeks in Count mode confirming the new detection matches what you see today, then move your alarms over and pick a sensitivity level you’re comfortable with. If you run a web ACL across several resources, or you manage rules through AWS Firewall Manager, contact AWS Support before you start so you don’t have to unwind anything later. The Shield Advanced application-layer automatic mitigation feature retires on January 1, 2027, and anything still relying on it needs to be migrated by then.

• Application layer (L7) DDoS protection documentation
• Introducing the AWS WAF Application Layer DDoS Protection
• AWS Shield Advanced metrics
• Migration helpers and CloudWatch comparison dashboard
• AWS WAF pricing
• AWS Shield Advanced pricing

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Reconstructing distributed denial of service (DDoS) attack traffic used to mean combining data from multiple sources after the fact. AWS Shield Advanced attack flow logs change that—they capture traffic metadata during attacks so you can pinpoint sources, verify mitigations, and feed your existing analysis pipelines.

Shield publishes logs to Amazon Simple Storage Service (Amazon S3), Amazon CloudWatch Logs, or Amazon Data Firehose using the same CloudWatch Logs delivery infrastructure as other AWS flow logs, so they fit directly into the monitoring and analysis tools you already use.

In this post, you will learn how Shield Advanced attack flow logs capture metadata during DDoS events, what each field in a flow log entry means, and how to enable and configure flow logging for your protected resources.

A DDoS attack floods an application with traffic, making it unavailable to users. Infrastructure-layer attacks saturate bandwidth and exhaust connection tables—you see packet loss and timeouts.

Shield Advanced is a managed DDoS protection service that detects and mitigates attacks for Amazon CloudFront distributions, Elastic Load Balancing load balancers, Amazon Route 53 hosted zones, AWS Global Accelerator standard accelerators, and Elastic IP (EIP) addresses. See the AWS Shield Advanced documentation for full coverage details. Initially, Shield Advanced will provide infrastructure-layer attack flow logs for EIP protections, with support for additional resource types to follow.

Flow logs help you understand attacks in several ways:

• Reconstruct traffic patterns – Query logs after an attack to analyze volume, source distribution, and protocol mix without relying only on aggregate CloudWatch metrics.
• Identify attack origins – The srccountry and location fields show where traffic originated and which AWS edge location it entered.
• Verify mitigation behavior – The action field records what Shield did with each flow.

Logs go to Amazon S3, CloudWatch Logs, or Data Firehose. You can then query them with Amazon Athena (a serverless query service for analyzing data in Amazon S3), route them to third-party Security Information and Event Management (SIEM) platforms or build CloudWatch Logs Insights queries (an interactive log analysis feature) without deploying new infrastructure.

Log records capture source and destination IP addresses and ports, protocol, packet and byte counts, the action Shield Advanced took, and TCP flags. They also include the AWS ingress location where traffic entered and a two-letter country code for the traffic source when available. Logs are written at 5-minute intervals and are available during an active attack and after it concludes.

The maximum file size is 75 MB. If a file reaches that limit within the 5-minute window, the file will be closed, published, and a new file will start. Flow logs support JSON, plain text, W3C, and Parquet output formats and contain the following fields:

The following steps walk you through creating the CloudWatch Logs delivery resources that connect a Shield Advanced protection to your preferred log destination.

Before configuring flow logs, make sure you have:

• An active Shield Advanced subscription
• At least one existing Shield Advanced protection
• AWS Identity and Access Management (IAM) permissions to create CloudWatch Logs delivery resources (logs:PutDeliverySource, logs:PutDeliveryDestination, logs:CreateDelivery)

Flow logs incur standard CloudWatch Logs vended log charges, and the destination resources (S3 bucket storage, CloudWatch Logs log group storage, or Firehose data processing) incur separate charges. Review the Vended Logs entry on the CloudWatch pricing page and the pricing for your chosen destination service before enabling flow logs on high-traffic resources.

Log delivery requires three objects:

• DeliverySource – Represents the Shield Advanced protection that produces the logs
• DeliveryDestination – Represents where logs should be sent (Amazon S3, CloudWatch Logs, or Amazon Data Firehose)
• Delivery – Connects the source to the destination

This three-object model lets you reuse destinations across multiple sources and manage delivery pipelines independently. For example, you can send logs from multiple Shield protections to the same S3 bucket by creating multiple DeliverySource objects that reference the same DeliveryDestination.

Because Shield Advanced attack flow logs use the CloudWatch Logs delivery infrastructure, you can aggregate them across accounts and Regions just like other vended logs. Deliver directly to a centralized S3 bucket with a cross-account policy, replicate CloudWatch Logs log groups using cross-account cross-Region centralization rules, or stream to a shared Firehose stream using cross-account subscriptions. Explore these options to build a unified view of DDoS attack traffic across your multi-account, multi-Region footprint.

Choose a destination:

• Option A – S3 bucket: Best for long-term storage and Athena queries. See Creating an S3 bucket.
• Option B – CloudWatch Logs log group: Best for real-time monitoring and CloudWatch Logs Insights. See Create a log group in CloudWatch Logs.
• Option C – Data Firehose delivery stream: Best for streaming to third-party tools and SIEMs. See Create a Firehose stream.

The destination resource needs a policy that grants the CloudWatch Logs delivery service write permissions. The policy varies by destination type. For more information, see Logs sent to Amazon S3, Logs sent to CloudWatch Logs, or Logs sent to Firehose.

For Amazon S3 destinations, you have two options:

• Automatic policy creation: If your bucket has no existing resource policy and you have the s3:GetBucketPolicy and s3:PutBucketPolicy permissions, AWS automatically creates the required policy when you create the delivery in step 6. You can skip to step 3.
• Manual policy update: If you need to customize the policy or your organization requires pre-approved policies, create the policy manually by following the instructions for Logs sent to Amazon S3.

Shield Advanced is a global service and uses the us-east-1 AWS Region for management. Run the following command to list your Shield Advanced protections.

aws shield list-protections \
  --region us-east-1

In the output, copy the ProtectionArn value for the protection you want to log.

Run the following command to create the delivery source, replace <protection-arn> with the ProtectionArn value from step 3.

aws logs put-delivery-source \
  --name my-shield-delivery-source \
  --resource-arn <protection-arn> \
  --log-type FLOW_LOGS \
  --region us-east-1

The --resource-arn is the ARN of your Shield Advanced protection—not the protected resource itself. Shield Advanced creates a separate protection object that wraps your resource, and flow logs are generated by that protection layer rather than the underlying resource.

Run the following command to create the delivery destination, replace <resource-arn> with the ARN of the destination resource you created in step 1.

aws logs put-delivery-destination \
  --name my-shield-delivery-destination \
  --output-format plain \
  --delivery-destination-configuration '{"destinationResourceArn":"<resource-arn>"}' \
  --region us-east-1

The --delivery-destination-configuration parameter takes a JSON object with a destinationResourceArn key whose value is the ARN of your S3 bucket, log group, or Firehose stream.

In the output, copy the value of the top-level ARN field—this is the delivery destination ARN (different from the bucket ARN). You will use this in step 6.

Run the following command to connect the delivery source to the delivery destination, replace <delivery-destination-arn> with the delivery destination ARN from step 5.

aws logs create-delivery \
  --delivery-source-name my-shield-delivery-source \
  --delivery-destination-arn <delivery-destination-arn> \
  --region us-east-1

Run the following command to confirm the delivery is active.

aws logs describe-deliveries \
  --region us-east-1

After delivery is active, Shield Advanced publishes flow log records to your destination during DDoS events.

To avoid ongoing charges, delete the resources you created.

1. Delete the delivery:

   aws logs delete-delivery \
     --id <delivery-id> \
     --region us-east-1

2. Delete the delivery source:

   aws logs delete-delivery-source \
     --name my-shield-delivery-source \
     --region us-east-1

3. Delete the delivery destination:

   aws logs delete-delivery-destination \
     --name my-shield-delivery-destination \
     --region us-east-1

4. (Optional) Back up flow log data if you need to retain logs for compliance or analysis.
5. Delete the destination resource. Warning: Deleting the destination resource will permanently delete all flow log data.

   For an S3 bucket:

   aws s3 rb s3://<bucket-name> \
     --force \
     --region <region>

   For a CloudWatch Logs log group:

   aws logs delete-log-group \
     --log-group-name <log-group-name> \
     --region <region>

   For a Firehose stream:

   aws firehose delete-delivery-stream \
     --delivery-stream-name <stream-name> \
     --region <region>

Shield Advanced attack flow logs provide the visibility you need to understand and respond to DDoS attacks effectively. By integrating with your existing observability infrastructure, they deliver actionable insights without requiring new tooling or complex setup. Enable flow logs on your Shield Advanced protections today to gain immediate visibility into attack patterns and strengthen your DDoS defense posture.

• Build an Athena table to query logs in Amazon S3
• Interactively search and analyze your log data in Amazon CloudWatch Logs
• Create CloudWatch alarms on attack patterns

For the full reference about flow log configuration, see the AWS Shield Advanced documentation.

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