Ldap Injection in Adonisjs with Dynamodb

LDAP Injection is an injection attack that occurs when an application passes unsanitized user input into LDAP query building logic. AdonisJS, a Node.js web framework, does not inherently provide LDAP-specific query builders, so developers often construct LDAP filters manually or via third-party LDAP clients. When these queries include user-controlled data without proper escaping, attackers can manipulate the filter syntax to bypass authentication, enumerate users, or extract sensitive directory information.

Using Amazon DynamoDB as the backend data store alongside AdonisJS can inadvertently expose LDAP-like query patterns if the application uses DynamoDB to store or retrieve directory-like data (e.g., user groups or permissions) that later influence LDAP filter construction. For example, if an endpoint accepts a username parameter, uses it to fetch user metadata from DynamoDB, and then embeds that metadata into an LDAP filter, an attacker can supply LDAP metacharacters (such as *, (, ), &) to alter the filter’s logic.

Consider an AdonisJS route where a username from the request is used to retrieve an employee record from DynamoDB and then used in an LDAP filter:

const { Base64 } = require('js-base64');
const { DynamoDBClient, GetItemCommand } = require('@aws-sdk/client-dynamodb');

async function buildLdapFilter(username) {
  const client = new DynamoDBClient({ region: 'us-east-1' });
  const command = new GetItemCommand({
    TableName: 'Employees',
    Key: { userId: { S: username } }
  });
  const response = await client.send(command);
  const employee = response.Item;
  // Unsafe: directly embedding user input and DynamoDB-derived values into LDAP filter
  const filter = `(&(objectClass=user)(uid=${username})(department=${employee.department?.S}))`;
  return filter;
}

If the username parameter contains an LDAP injection payload such as admin)(&objectClass=*), the resulting filter becomes (&(objectClass=user)(uid=admin)(&objectClass=*)(department=...)), which can bypass intended matching logic. Similarly, malicious input can change group membership checks or extract data via chained filters. Because DynamoDB stores the department and other attributes, an attacker may also probe for unusual attribute names or leverage DynamoDB error messages to infer schema, aiding injection. The combination of dynamic query building in AdonisJS, user-controlled input, and data stored in DynamoDB creates a path for LDAP injection that can compromise identity verification and data access controls.

Remediation centers on strict input validation, canonicalization, and avoiding direct string interpolation when constructing any query-like structures, including LDAP filters. For DynamoDB, use the AWS SDK’s built-in condition and expression builders to avoid injection through expression attribute names or values. When data from DynamoDB is used in downstream protocols such as LDAP, treat all data as untrusted and apply escaping appropriate for the target protocol.

1. Validate and sanitize the username input before using it in any lookup or filter. Allow only expected patterns (e.g., alphanumeric with limited special characters) and reject inputs containing LDAP metacharacters if they are not explicitly needed.

2. Use parameterized expressions with DynamoDB SDK operations instead of concatenating attribute names or values. For read operations, prefer GetItemCommand with exact key values, and avoid building search filters via string concatenation. When querying, use ScanCommand with a filter expression that references expression attribute values, not user input directly.

3. Escape or encode any data from DynamoDB before incorporating it into an LDAP filter. For example, escape parentheses, asterisks, and backslashes according to RFC 4515.

Safe AdonisJS controller example with DynamoDB and LDAP filter construction:

const { DynamoDBClient, GetItemCommand } = require('@aws-sdk/client-dynamodb');
const { escapeLdapFilterComponent } = require('./ldapUtils'); // custom sanitizer

async function safeBuildLdapFilter(username) {
  const client = new DynamoDBClient({ region: 'us-east-1' });
  // Validate username format strictly
  if (!/^[a-zA-Z0-9._-]{3,64}$/.test(username)) {
    throw new Error('Invalid username');
  }

  const command = new GetItemCommand({
    TableName: 'Employees',
    Key: { userId: { S: username } }
  });
  const response = await client.send(command);
  const item = response.Item;

  if (!item) {
    throw new Error('User not found');
  }

  const department = item.department?.S || '';
  const safeUsername = escapeLdapFilterComponent(username);
  const safeDept = escapeLdapFilterComponent(department);

  // Safe: components are escaped for LDAP filter syntax
  const filter = `(&(objectClass=user)(uid=${safeUsername})(department=${safeDept}))`;
  return filter;
}

// ldapUtils.js
function escapeLdapFilterComponent(value) {
  // Escape *, (, ), \0, and backslash as per RFC 4515
  return String(value).replace(/([*()\\\x00])/g, '\\$1');
}
module.exports = { escapeLdapFilterComponent };

For DynamoDB queries that involve user input, use expression attribute names and values rather than string concatenation. Example of a safe DynamoDB query using the SDK within an AdonisJS service:

const { DynamoDBClient, QueryCommand } = require('@aws-sdk/client-dynamodb');

async function queryEmployeesByDepartment(deptName) {
  const client = new DynamoDBClient({ region: 'us-east-1' });
  // Validate department name
  if (!/^[a-zA-Z0-9 _-]{1,100}$/.test(deptName)) {
    throw new Error('Invalid department');
  }

  const command = new QueryCommand({
    TableName: 'Employees',
    IndexName: 'DepartmentIndex',
    KeyConditionExpression: 'department = :dept',
    ExpressionAttributeValues: {
      ':dept': { S: deptName }
    }
  });
  const response = await client.send(command);
  return response.Items;
}

By combining strict input validation, safe DynamoDB SDK usage, and LDAP-aware escaping, the AdonisJS application reduces the risk of LDAP injection when user-controlled data and DynamoDB-stored attributes are involved. These practices align with secure coding guidance for identity and directory integrations and help ensure that filters remain semantically correct and resistant to manipulation.