Privilege Escalation in Feathersjs with Dynamodb

In a FeathersJS service that uses Dynamodb as the persistence layer, privilege escalation often occurs when authorization checks are incomplete or applied inconsistently between service methods. FeathersJS is framework-agnostic about data storage; it relies on service hooks and the caller-provided parameters to enforce permissions. If a service does not validate ownership or role-based access on each request, an authenticated user can modify parameters—such as the primary key or filter—to access or mutate records that should be restricted.

Dynamodb’s model amplifies this risk when queries construct KeyConditionExpressions or FilterExpressions from user input without strict validation. For example, a typical FeathersJS find method might forward a query like userId=me to a Dynamodb query, but if the service does not explicitly override the query to bind the request identity to the KeyConditionExpression, a user can inject a different userId value and enumerate or operate on other users’ items. This is a BOLA/IDOR pattern, and in the context of the 12 checks run by middleBrick, it surfaces as a privilege escalation finding when the scanner observes that unauthenticated or low-privilege contexts can reach endpoints that should be constrained by ownership or role.

With middleBrick’s scans, such misconfigurations are detected across the 12 security checks, including BOLA/IDOR and Property Authorization. The scanner evaluates whether runtime behavior aligns with the intended policy expressed in the OpenAPI specification and service hooks. In FeathersJS + Dynamodb setups, common root causes include missing hook-level guards, improper use of params.account or params.user, and Dynamodb expressions that do not bind the partition key to the authenticated subject. Because the scan is black-box and unauthenticated, it can reveal endpoints where a low-privilege token or no token permits querying or modifying records that should be isolated by user or role, thereby exposing a privilege escalation path.

Consider a service that allows admins to list all sessions but fails to enforce scope checks on the Dynamodb query. An attacker authenticating as a low-privilege user could adjust the filter to request a broader scan or attempt to leverage secondary index queries if the service exposes them without ownership constraints. The middleBrick LLM/AI Security checks further probe whether endpoints leak system prompts or allow prompt injection, which can compound risks if administrative instructions are exposed through verbose error messages or misconfigured logging.

Remediation guidance centers on enforcing strict ownership in hooks and ensuring Dynamodb expressions are parameterized with the subject’s identity rather than client-provided values. Combine this with rate limiting and input validation to reduce abuse surfaces. Using the middleBrick CLI, teams can integrate scans into scripts and fail builds when risk thresholds are exceeded, while the Web Dashboard enables tracking scores over time to verify that privilege escalation vectors are closed.

To remediate privilege escalation in FeathersJS with Dynamodb, bind every query to the authenticated subject and avoid passing raw user input into KeyConditionExpression or FilterExpression. Below are concrete, working examples that illustrate secure patterns.

Secure find with ownership binding

Ensure the service hook enforces ownership by rewriting the query before it reaches Dynamodb. This example assumes user identity is available in params.user.id.

const { DynamoDBClient, QueryCommand } = require("@aws-sdk/client-dynamodb");
const client = new DynamoDBClient({ region: "us-east-1" });

module.exports = function (options = {}) {
  return async context => {
    const userId = context.params.user?.id;
    if (!userId) {
      throw new Error("Unauthenticated");
    }

    const command = new QueryCommand({
      TableName: "UserSessions",
      KeyConditionExpression: "userId = :uid",
      ExpressionAttributeValues: {
        ":uid": { S: userId }
      },
      FilterExpression: "status = :active",
      ExpressionAttributeValues: {
        ...ExpressionAttributeValues,
        ":active": { S: "active" }
      }
    });

    const result = await client.send(command);
    context.result = {
      total: result.Count,
      limit: context.params.pagination.$limit,
      data: result.Items || []
    };
    return context;
  };
};

Service hook overriding id field for get/update/remove

Prevent users from changing the ID in the request payload by overriding id from params so that only the record owned by the subject is targeted.

module.exports = {
  before: {
    async get(id, params) {
      params.id = params.user.id; // force ownership
      return params;
    },
    async find(params) {
      if (!params.query.userId) {
        params.query.userId = params.user.id;
      }
      return params;
    },
    async create(data, params) {
      data.userId = params.user.id;
      return data;
    }
  }
};

Dynamodb ConditionExpression for updates with ownership

When updating or deleting, add a condition that the subject owns the item. This prevents horizontal privilege escalation where a user updates another user’s record by guessing IDs.

const { DynamoDBClient, UpdateCommand } = require("@aws-sdk/client-dynamodb");
const client = new DynamoDBClient({ region: "us-east-1" });

async function safeUpdate(userId, itemId, updateExpression, expressionAttributeValues) {
  const command = new UpdateCommand({
    TableName: "UserProfiles",
    Key: {
      userId: { S: userId },
      itemId: { S: itemId }
    },
    UpdateExpression: updateExpression,
    ConditionExpression: "userId = :uid",
    ExpressionAttributeValues: {
      ...expressionAttributeValues,
      ":uid": { S: userId }
    }
  });

  const response = await client.send(command);
  return response;
}

Using middleBrick integrations for ongoing validation

Leverage the middleBrick CLI to scan from the terminal and the GitHub Action to add API security checks to your CI/CD pipeline. The dashboard helps track your API security scores over time, and the MCP Server lets you scan APIs directly from your AI coding assistant to catch regressions early.

These code samples ensure that privilege escalation risks are minimized by anchoring every Dynamodb operation to the authenticated subject, validating input, and enforcing role-based constraints at the hook level.