API-Specific DDoS Protection Strategies

APIs face unique DDoS challenges compared to traditional web applications. Attackers can exploit computationally expensive endpoints, create resource exhaustion through nested queries, or abuse batch operations. Protecting APIs requires understanding these specific attack vectors and implementing targeted defenses.

Query complexity analysis prevents resource exhaustion attacks in GraphQL and similar APIs. Calculate query cost based on field selections, nesting depth, and pagination parameters. Reject queries exceeding complexity thresholds before execution. This approach prevents single requests from consuming excessive server resources.

// GraphQL query complexity analysis
const depthLimit = require('graphql-depth-limit');
const costAnalysis = require('graphql-cost-analysis');

const schema = buildSchema(`
  type Query {
    users(limit: Int): [User]
    user(id: ID!): User
  }
  
  type User {
    id: ID!
    name: String
    posts(limit: Int): [Post]
    followers(limit: Int): [User]
  }
  
  type Post {
    id: ID!
    title: String
    content: String
    author: User
    comments(limit: Int): [Comment]
  }
`);

// Configure complexity limits
const server = new GraphQLServer({
    schema,
    validationRules: [
        depthLimit(5), // Maximum query depth
        costAnalysis({
            maximumCost: 1000,
            defaultCost: 1,
            variables: {},
            createError: (max, actual) => {
                return new Error(`Query exceeded maximum cost of ${max}. Actual cost: ${actual}`);
            },
            onComplete: (cost) => {
                console.log(`Query cost: ${cost}`);
            }
        })
    ]
});

// Custom cost calculation
const customCostAnalysis = {
    maximumCost: 1000,
    fieldCosts: {
        User: {
            posts: (args) => args.limit || 10,
            followers: (args) => args.limit || 10
        },
        Post: {
            comments: (args) => args.limit || 5
        }
    }
};

Implementing request queuing and prioritization helps maintain service during attack conditions. High-priority requests from authenticated users or critical operations receive preferential treatment. Background tasks and low-priority requests face aggressive throttling during high load. This approach ensures essential functionality remains available even under attack.