Broken Authentication in Strapi with Dynamodb

Strapi is a headless CMS that often uses Amazon DynamoDB as a persistence layer for custom content types and plugin data. When authentication logic is implemented at the Strapi level without strict validation of DynamoDB access patterns, broken authentication can occur. This typically happens when access control is enforced only in application code while DynamoDB permissions remain overly permissive.

Consider a Strapi plugin that stores user sessions in DynamoDB. If the IAM policy attached to the DynamoDB table allows broad dynamodb:GetItem and dynamodb:Query actions without scoping to a specific partition key (e.g., user_id), an authenticated user can manipulate request parameters to access another user’s session record. For example, changing a URL parameter like session_id=abc123 to session_id=def456 may return another user’s session if DynamoDB permissions do not enforce ownership checks.

In a typical Strapi controller, you might see:

// Strapi controller (vulnerable example)
module.exports = {
  async getSession(ctx) {
    const { sessionId } = ctx.params;
    const dynamo = new AWS.DynamoDB.DocumentClient();
    const params = {
      TableName: process.env.SESSION_TABLE,
      Key: { session_id: sessionId },
    };
    const data = await dynamo.get(params).promise();
    ctx.body = data.Item;
  },
};

This code trusts sessionId from the request without verifying that the session belongs to the requesting user. DynamoDB will return the item if the provided key exists and the caller has generic read permissions, leading to IDOR (Insecure Direct Object Reference) via broken authentication.

Additionally, if Strapi’s authentication middleware issues JSON Web Tokens with weak signing algorithms (e.g., none) or predictable secrets, an attacker can forge tokens and make authenticated requests that DynamoDB honors according to the token’s identity. Misconfigured DynamoDB fine-grained access control can further allow token holders to list or scan tables, expanding the impact of broken authentication beyond a single record access.

Compliance mappings: OWASP API Top 10 2023 Broken Authentication, CWE-287, and relevant to PCI-DSS authentication requirements. Findings of this nature are included in middleBrick scans under the Authentication and BOLA/IDOR checks.

Remediation requires aligning DynamoDB access patterns with Strapi’s authentication context. Always scope DynamoDB requests to the authenticated user’s identity and enforce ownership checks before returning data.

Use IAM policies that restrict DynamoDB actions to keys derived from the authenticated user. For example, enforce a condition that the partition key must match the user’s identifier from the validated token:

// IAM policy snippet (JSON) – apply in AWS
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "dynamodb:GetItem",
        "dynamodb:Query"
      ],
      "Resource": "arn:aws:dynamodb:region:account:table/sessions",
      "Condition": {
        "ForAllValues:StringEquals": {
          "dynamodb:LeadingKeys": ["${cognito-identity.amazonaws.com:sub}"]
        }
      }
    }
  ]
}

In Strapi, update the controller to extract the user identity from the validated authentication context and use it as the partition key:

// Strapi controller (secure example)
module.exports = {
  async getSession(ctx) {
    const user = ctx.state.user; // authenticated user from Strapi middleware
    if (!user) {
      ctx.unauthorized();
      return;
    }
    const { sessionId } = ctx.params;
    const dynamo = new AWS.DynamoDB.DocumentClient();
    const params = {
      TableName: process.env.SESSION_TABLE,
      Key: {
        user_id: user.id,   // enforce ownership via partition key
        session_id: sessionId,
      },
    };
    const data = await dynamo.get(params).promise();
    if (!data.Item) {
      ctx.notFound();
      return;
    }
    ctx.body = data.Item;
  },
};

For token-based systems, validate the token signature and claims rigorously. Prefer using AWS Cognito with custom authorizers or OAuth introspection to ensure the subject in the token matches the DynamoDB key. Also, enable DynamoDB encryption at rest and use least-privilege IAM roles for the application to reduce the impact of compromised credentials.

middleBrick scans can surface these risks under Authentication, BOLA/IDOR, and Unsafe Consumption checks. The Pro plan’s continuous monitoring can alert you if future changes weaken these controls, and the GitHub Action can fail builds when insecure patterns are detected in IaC or configuration.