Bola Idor in Strapi with Dynamodb

Broken Object Level Authorization (BOLA) occurs when an API fails to enforce authorization checks between a user and a specific resource identifier. In Strapi with DynamoDB as the persistence layer, BOLA can arise from a mismatch between how identifiers are exposed to the client and how the backend validates permissions against those identifiers.

Strapi typically uses numeric or UUID primary keys that are directly usable as record identifiers in URLs and API responses. When DynamoDB is used as the data store, each record is stored with a primary key composed of a partition key (and optionally a sort key). If Strapi exposes these raw keys as resource identifiers in REST or GraphQL endpoints without contextual ownership checks, an authenticated user can manipulate the identifier to access another user’s record.

Consider a content management scenario where authors manage articles. An endpoint like /articles/:id might retrieve an article by its DynamoDB key. If Strapi does not scope the request to the authenticated user’s organization or tenant, an attacker can enumerate valid article IDs and read or modify articles they do not own. This is a classic BOLA: the object identifier is predictable or enumerable, and authorization is not re-validated at the data access layer.

DynamoDB-specific factors can amplify the risk. Because DynamoDB requires explicit key construction for queries and scans, Strapi’s data access layer must correctly map incoming identifiers to partition and sort key values. If this mapping is implemented naively—such as using the client-supplied id directly as the partition key without verifying it belongs to the requesting user’s scope—an attacker can supply arbitrary keys to access unrelated items. Additionally, secondary indexes used by Strapi can introduce further exposure if they do not mirror the same ownership constraints as the base table, allowing lateral movement across indexed data.

Operational factors also matter. In a multi-tenant setup, tenant identifiers must be part of the key schema and enforced on every request. If tenant context is derived only from authentication metadata and not validated against the key attributes in DynamoDB, BOLA persists. For example, an attacker could modify a tenant ID in a query parameter or header and access data belonging to other tenants, provided the underlying DynamoDB keys remain predictable.

Real-world attack patterns mirror known CVE types seen in API authorization flaws, aligned with OWASP API Top 10:2023 A1 — Broken Object Level Authorization. Because Strapi can auto-generate CRUD endpoints when using DynamoDB, developers must explicitly scope data retrieval to the requester’s context, ensuring that object identifiers are not used in isolation without tenant or ownership validation.

Remediation centers on enforcing ownership and tenant context at the point where Strapi constructs DynamoDB queries. Never trust incoming identifiers; instead, derive keys from authenticated context and bind them to the request scope.

First, ensure your DynamoDB table includes tenant or user attributes as part of the key schema. For example, use a composite partition key like tenantId#userId or enforce tenantId as the partition key and use a sort key like articleId. This design ensures that queries without the correct tenant context cannot locate unrelated items.

In Strapi, customize the controller or service that resolves records to inject tenant and user context before querying DynamoDB. Below is a simplified example of a Strapi service using the AWS SDK for JavaScript v3 to fetch an article safely:

import { DynamoDBClient, GetItemCommand } from "@aws-sdk/client-dynamodb";

const client = new DynamoDBClient({ region: "us-east-1" });

export async function findArticleByOwner(userId, articleId, tenantId) {
  const key = {
    PK: { S: `TENANT#${tenantId}#USER#${userId}#ARTICLE#${articleId}` },
    SK: { S: `ARTICLE#${articleId}` }
  };
  const command = new GetItemCommand({
    TableName: process.env.DYNAMODB_TABLE_NAME,
    Key: key
  });
  const response = await client.send(command);
  return response.Item ? fromDynamoDBItem(response.Item) : null;
}

function fromDynamoDBItem(item) {
  return {
    id: item.PK.S.split('#').pop(),
    title: item.title?.S,
    content: item.content?.S,
    tenantId: item.PK.S.split('#')[1]
  };
}

This approach binds the article identifier to both the user and the tenant, preventing an attacker from substituting another article ID. The incoming articleId is combined with authenticated user and tenant values to construct the full DynamoDB key, ensuring that only records explicitly associated with the requester are returned.

For listing articles, avoid scanning the entire table. Instead, use a query that includes the tenant and user partition key:

import { DynamoDBClient, QueryCommand } from "@aws-sdk/client-dynamodb";

export async function listArticlesForUser(userId, tenantId, limit = 20) {
  const client = new DynamoDBClient({ region: "us-east-1" });
  const command = new QueryCommand({
    TableName: process.env.DYNAMODB_TABLE_NAME,
    KeyConditionExpression: "PK = :pk AND begins_with(SK, :sk)",
    ExpressionAttributeValues: {
      ":pk": { S: `TENANT#${tenantId}#USER#${userId}` },
      ":sk": { S: "ARTICLE#" }
    },
    Limit: limit
  });
  const response = await client.send(command);
  return response.Items?.map(fromDynamoDBItem) || [];
}

In Strapi admin panels and API responses, ensure that identifiers exposed to the client do not reveal raw DynamoDB keys that could be manipulated. Use opaque references or map internal keys to stable, non-sequential identifiers when necessary, and always re-validate ownership on each request using server-side logic.

Finally, audit your data access layer to confirm that every DynamoDB operation includes tenant and user context derived from the authenticated session, not from untrusted client input. This practice mitigates BOLA by design, aligning object identifiers with the requester’s authorization scope.