A Complete Guide for AWS WAF

What is AWS WAF?

Basic Workflow of AWS WAF?

AWS Web Application Firewall (AWS WAF) can be applied to the following resources

Amazon CloudFront Distributions: AWS WAF can protect web applications and APIs that are served by Amazon CloudFront, AWS’s global Content Delivery Network (CDN). By integrating with CloudFront, AWS WAF provides protection at the edge locations, reducing the latency for users.

Application Load Balancers (ALB): AWS WAF can be used to protect applications served through Application Load Balancers. This is typically used in conjunction with Amazon Elastic Load Balancing (ELB) to distribute traffic among multiple EC2 instances or containers.

Amazon API Gateway: AWS WAF can be used to secure APIs managed by Amazon API Gateway. This helps in protecting APIs against common web exploits and bots that can affect availability, compromise security, or consume excessive resources.

AWS App Runner: AWS WAF can also be used with AWS App Runner, a fully managed service that makes it easy for developers to quickly deploy containerized web applications and APIs, at scale, with no prior infrastructure experience required.

List of CloudWatch Metrices for AWS Application LoadBalancer

Here is a list of CloudWatch metrics for an AWS Application Load Balancer (ALB) presented in tabular format:

List of CloudWatch Metrices for AWS Api Gateway

Here is a list of CloudWatch metrics for AWS API Gateway presented

List of CloudWatch Metrices for AWS Application LoadBalancer which is for AWS WAF and DDOS

Here is a list of CloudWatch metrics specifically related to AWS WAF (Web Application Firewall) and DDoS (Distributed Denial of Service) protection for an AWS Application Load Balancer (ALB), presented in tabular format:

Steps to Determine the Threshold Value

Calculate the Transactions Per Minute:

• Since you have 2 crore (20 million) transactions each day, first, determine the transactions per second.

Consider Peak Load:

• Traffic often has peak periods. If peak traffic is double the average, then consider this for the threshold.
• Peak Transactions Per Minute (TPM):

Set the Threshold:

• Based on the peak transactions, you can set your AWS WAF threshold.
• The threshold should be slightly higher than the peak to avoid false positives but within a reasonable range to catch malicious activity.
• Recommended Threshold: 30,000 transactions per 60 seconds

Recommended Threshold:

DDOS transaction calculator Ecxel Sheet

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Differnece between AWS WAF ACLS Vs Rules Vs Conditions

Here is a comparison of AWS WAF ACLs, Rules, and Conditions presented in tabular format to highlight their differences:

List of recommended value for AWS WAF to avoid DDOS attack on AWS ELB

To effectively protect your AWS Elastic Load Balancer (ELB) from Distributed Denial of Service (DDoS) attacks using AWS Web Application Firewall (WAF), it’s important to configure various rules and limits to mitigate the attack vectors. Here’s a list of recommended values and configurations for AWS WAF to enhance protection:

1. IP Rate-based Rules

• Limit: Set a rate limit on requests from a single IP address. A typical value could be 2,000 requests per 5 minutes (400 requests per minute).

2. IP Block/Allow Lists

• Trusted IP List: Allow known, trusted IP addresses.
• Blocked IP List: Block known malicious IP addresses or ranges. Update this list based on threat intelligence feeds.

3. Geo-Blocking

• Country Blocking: Block traffic from countries where you do not expect legitimate traffic.

4. SQL Injection Rule

• SQL Injection Detection: Enable SQL injection detection rule to block requests containing SQL injection attempts.

5. XSS Rule

• Cross-Site Scripting (XSS) Detection: Enable XSS detection rule to block requests containing cross-site scripting payloads.

6. Size Constraint Rule

• Request Size Limit: Set a maximum size for request headers and bodies. A typical value is 10 KB for headers and 100 KB for bodies.

7. Request Rate Limit

• Rate-based Rule: Implement rate-based rules to automatically block IPs that exceed a specified rate of requests. Example value: 1,000 requests in a 5-minute period.

8. Regular Expressions Pattern Sets

• Custom Rules: Create custom rules using regular expressions to detect and block patterns typical of malicious traffic.

9. Managed Rule Groups

• AWS Managed Rules: Use AWS Managed Rules for common threats, which are regularly updated by AWS.
  • AWSManagedRulesCommonRuleSet
  • AWSManagedRulesKnownBadInputsRuleSet
  • AWSManagedRulesLinuxRuleSet
  • AWSManagedRulesSQLiRuleSet

10. Custom Rule Groups

• Application-specific Rules: Create custom rule groups tailored to your specific application requirements and traffic patterns.

11. Rate Limit for Specific URIs

• URI Rate Limiting: Apply rate limits to specific URIs that are more susceptible to abuse (e.g., login pages, search endpoints). Example value: 100 requests per minute per IP.

12. Header Constraint Rule

• Header Size Limit: Enforce size limits on request headers. Example values: 8 KB for headers, 512 bytes for individual header fields.

13. JSON and XML Body Parsing

• Inspection: Enable inspection of JSON and XML bodies to detect and block malicious payloads.

14. Automation and Monitoring

• AWS Shield Advanced: Use AWS Shield Advanced for enhanced DDoS protection and automated attack mitigation.
• AWS CloudWatch: Set up CloudWatch alarms to monitor for spikes in traffic and other anomalies.

15. Logging and Analysis

• AWS WAF Logging: Enable logging to analyze requests and fine-tune your rules based on real traffic data.

Example Configuration Summary

1. Rate Limit per IP: 2,000 requests per 5 minutes
2. Request Size Limit: Headers: 10 KB, Bodies: 100 KB
3. Rate-based Rule: 1,000 requests per 5 minutes
4. URI-specific Rate Limit: 100 requests per minute per IP

AWS WAF RULE ACTION

Here’s a detailed description of AWS WAF rule actions in a tabular format:

Example terraform code

Write a terraform code where you set the sample list of value for AWS WAF to avoid DDOS attack on AWS ELB

provider "aws" {
  region = "us-west-2"
}

# Create a WAFv2 Web ACL
resource "aws_wafv2_web_acl" "example" {
  name        = "example-web-acl"
  description = "Example Web ACL to mitigate DDoS attacks"
  scope       = "REGIONAL"
  default_action {
    allow {}
  }
  visibility_config {
    cloudwatch_metrics_enabled = true
    metric_name                = "exampleWebACL"
    sampled_requests_enabled   = true
  }
}

# IP set for allowed IPs
resource "aws_wafv2_ip_set" "allow_list" {
  name        = "allow-list"
  description = "List of allowed IPs"
  scope       = "REGIONAL"
  ip_address_version = "IPV4"
  addresses = [
    "192.0.2.0/24", # example IP range
  ]
}

# IP set for blocked IPs
resource "aws_wafv2_ip_set" "block_list" {
  name        = "block-list"
  description = "List of blocked IPs"
  scope       = "REGIONAL"
  ip_address_version = "IPV4"
  addresses = [
    "203.0.113.0/24", # example malicious IP range
  ]
}

# Rate limit rule
resource "aws_wafv2_rule_group" "rate_limit" {
  name        = "rate-limit"
  description = "Rate limit rule group"
  scope       = "REGIONAL"
  capacity    = 100

  visibility_config {
    cloudwatch_metrics_enabled = true
    metric_name                = "rateLimitRuleGroup"
    sampled_requests_enabled   = true
  }

  rule {
    name     = "RateLimitRule"
    priority = 1
    action {
      block {}
    }
    statement {
      rate_based_statement {
        limit          = 2000
        aggregate_key_type = "IP"
      }
    }
    visibility_config {
      cloudwatch_metrics_enabled = true
      metric_name                = "rateLimitRule"
      sampled_requests_enabled   = true
    }
  }
}

# SQL Injection Rule
resource "aws_wafv2_rule_group" "sql_injection" {
  name        = "sql-injection"
  description = "SQL Injection rule group"
  scope       = "REGIONAL"
  capacity    = 50

  visibility_config {
    cloudwatch_metrics_enabled = true
    metric_name                = "sqlInjectionRuleGroup"
    sampled_requests_enabled   = true
  }

  rule {
    name     = "SQLInjectionRule"
    priority = 2
    action {
      block {}
    }
    statement {
      sqli_match_statement {
        field_to_match {
          query_string {}
        }
        text_transformation {
          priority = 1
          type     = "URL_DECODE"
        }
      }
    }
    visibility_config {
      cloudwatch_metrics_enabled = true
      metric_name                = "sqlInjectionRule"
      sampled_requests_enabled   = true
    }
  }
}

# Add rules to Web ACL
resource "aws_wafv2_web_acl_association" "example_association" {
  resource_arn = aws_lb.example.arn
  web_acl_arn  = aws_wafv2_web_acl.example.arn
}

resource "aws_wafv2_web_acl_rule" "allow_rule" {
  name     = "AllowRule"
  priority = 1
  action {
    allow {}
  }
  statement {
    ip_set_reference_statement {
      arn = aws_wafv2_ip_set.allow_list.arn
    }
  }
  visibility_config {
    cloudwatch_metrics_enabled = true
    metric_name                = "allowRule"
    sampled_requests_enabled   = true
  }
  web_acl_arn = aws_wafv2_web_acl.example.arn
}

resource "aws_wafv2_web_acl_rule" "block_rule" {
  name     = "BlockRule"
  priority = 2
  action {
    block {}
  }
  statement {
    ip_set_reference_statement {
      arn = aws_wafv2_ip_set.block_list.arn
    }
  }
  visibility_config {
    cloudwatch_metrics_enabled = true
    metric_name                = "blockRule"
    sampled_requests_enabled   = true
  }
  web_acl_arn = aws_wafv2_web_acl.example.arn
}

resource "aws_wafv2_web_acl_rule" "rate_limit_rule" {
  name     = "RateLimitRule"
  priority = 3
  action {
    block {}
  }
  statement {
    rate_based_statement {
      limit          = 2000
      aggregate_key_type = "IP"
    }
  }
  visibility_config {
    cloudwatch_metrics_enabled = true
    metric_name                = "rateLimitRule"
    sampled_requests_enabled   = true
  }
  web_acl_arn = aws_wafv2_web_acl.example.arn
}

resource "aws_wafv2_web_acl_rule" "sql_injection_rule" {
  name     = "SQLInjectionRule"
  priority = 4
  action {
    block {}
  }
  statement {
    sqli_match_statement {
      field_to_match {
        query_string {}
      }
      text_transformation {
        priority = 1
        type     = "URL_DECODE"
      }
    }
  }
  visibility_config {
    cloudwatch_metrics_enabled = true
    metric_name                = "sqlInjectionRule"
    sampled_requests_enabled   = true
  }
  web_acl_arn = aws_wafv2_web_acl.example.arn
}

# Sample ALB resource for association
resource "aws_lb" "example" {
  name               = "example-alb"
  internal           = false
  load_balancer_type = "application"
  security_groups    = [aws_security_group.lb_sg.id]
  subnets            = aws_subnet.public.*.id

  enable_deletion_protection = true
}

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