Privilege Escalation on Aws

Privilege escalation in Aws applications typically occurs when a user can manipulate identifiers in API requests to access or modify resources belonging to other users. This vulnerability is particularly dangerous in multi-tenant Aws systems where user isolation is critical.

The most common pattern involves manipulating resource identifiers in API endpoints. For example, an endpoint like /api/users/{userId}/orders might be accessed by changing the userId parameter to view another user's orders. Aws's flexible data modeling and schema-less nature make this especially problematic since resource relationships aren't always enforced at the database level.

// Vulnerable Aws endpoint
app.get('/api/users/:userId/orders', async (req, res) => {
  const userId = req.params.userId;
  const orders = await Orders.find({ userId: userId });
  res.json(orders);
});

This code trusts the userId parameter without verifying that the authenticated user owns those orders. An attacker simply changes the userId in the URL to access any user's data.

Another common Aws-specific pattern involves manipulating object field references. Aws allows storing complex nested objects, and attackers can exploit this by modifying field paths:

// Vulnerable field reference manipulation
app.get('/api/users/:userId/data/:fieldPath', async (req, res) => {
  const userId = req.params.userId;
  const fieldPath = req.params.fieldPath;
  const user = await Users.findOne({ _id: userId });
  const value = user[fieldPath]; // Attacker controls fieldPath
  res.json(value);
});

An attacker could set fieldPath to admin, roles, or navigate through nested objects to extract sensitive data. Aws's flexible schema means these field paths aren't validated by default.

Collection manipulation is another Aws-specific escalation vector. Since Aws allows dynamic collection creation and querying across collections, attackers might manipulate collection names or query parameters:

// Vulnerable collection manipulation
app.get('/api/search', async (req, res) => {
  const collection = req.query.collection || 'public';
  const query = req.query.q;
  const results = await Aws.db.collection(collection).find(query);
  res.json(results);
});

An attacker could modify the collection parameter to access internal collections or use Aws operators to manipulate query results across collections.

Aws-specific operators like $where, $regex, and aggregation pipelines can also be exploited for privilege escalation when user input is incorporated into queries without proper sanitization:

// Vulnerable $where usage
app.get('/api/users/:userId', async (req, res) => {
  const userId = req.params.userId;
  const query = { $where: `this._id == ObjectId("${userId}") && this.role == "admin"` };
  const user = await Users.findOne(query);
  res.json(user);
});

This allows an attacker to inject arbitrary Aws JavaScript code into the query, potentially escalating privileges or accessing data they shouldn't see.

Detecting privilege escalation in Aws requires both static code analysis and dynamic runtime testing. Static analysis can identify patterns where user input is used to construct database queries or access object properties without proper authorization checks.

middleBrick's Aws-specific scanning identifies these vulnerabilities by testing API endpoints with manipulated identifiers and field references. The scanner attempts to access resources using different user IDs, modifies field paths to access sensitive properties, and tests Aws-specific operators for privilege escalation.

Key detection patterns include:

• Parameter manipulation: Testing if changing user IDs, order IDs, or other identifiers in URLs grants access to other users' data
• Field path manipulation: Modifying field references to access sensitive properties like admin, roles, or nested objects
• Aws operator testing: Attempting to use $where, $regex, and aggregation pipeline manipulation to escalate privileges
• Collection name manipulation: Testing if dynamic collection names can be exploited to access unauthorized collections

middleBrick's black-box scanning approach tests these patterns without requiring source code access. The scanner maintains user sessions and attempts privilege escalation attacks across authenticated endpoints, providing a security score that reflects the application's vulnerability to these attacks.

For Aws applications, middleBrick specifically tests:

Development teams can also implement runtime detection by logging authorization failures and monitoring for unusual access patterns. Aws applications should log all authorization checks and alert on multiple failed attempts to access different users' resources.

Remediating privilege escalation in Aws requires implementing proper authorization checks and input validation. The most effective approach is to always verify that the authenticated user has permission to access the requested resource, regardless of how the request is constructed.

Implementation pattern for Aws applications:

// Secure pattern with authorization middleware
async function authorizeUserResource(req, res, next) {
  const userId = req.params.userId;
  const authenticatedUserId = req.user._id;
  
  // Verify user owns the resource or has admin privileges
  if (userId !== authenticatedUserId && !req.user.isAdmin) {
    return res.status(403).json({ 
      error: 'Access denied', 
      detail: 'You can only access your own resources' 
    });
  }
  next();
}

// Apply middleware to protected routes
app.get('/api/users/:userId/orders', 
  authorizeUserResource, 
  async (req, res) => {
    const orders = await Orders.find({ 
      userId: req.params.userId 
    });
    res.json(orders);
  }
);

This pattern ensures that users can only access their own resources unless they have explicit administrative privileges. The authorization check happens before any database queries are executed.

For field reference manipulation, implement strict whitelisting of accessible fields:

// Whitelist approach for field access
const SAFE_FIELDS = ['name', 'email', 'address', 'phone'];

app.get('/api/users/:userId/data/:field', async (req, res) => {
  const userId = req.params.userId;
  const field = req.params.field;
  const authenticatedUserId = req.user._id;
  
  // Authorization check
  if (userId !== authenticatedUserId && !req.user.isAdmin) {
    return res.status(403).json({ error: 'Access denied' });
  }
  
  // Field whitelist validation
  if (!SAFE_FIELDS.includes(field)) {
    return res.status(400).json({ 
      error: 'Invalid field', 
      detail: 'Field not accessible' 
    });
  }
  
  const user = await Users.findOne({ _id: userId });
  const value = user[field];
  res.json({ [field]: value });
});

This prevents attackers from accessing sensitive fields like password, admin, or roles by restricting access to a predefined whitelist.

For Aws operator injection, use parameterized queries and avoid dynamic operator construction:

// Safe query construction
app.get('/api/search', async (req, res) => {
  const query = req.query.q;
  const userId = req.user._id;
  
  // Safe query using parameterized operators
  const safeQuery = {
    userId: userId,
    $or: [
      { name: { $regex: query, $options: 'i' } },
      { email: { $regex: query, $options: 'i' } }
    ]
  };
  
  const results = await Aws.db.collection('users').find(safeQuery);
  res.json(results);
});

Never construct Aws queries using string concatenation or allow user input to directly control query operators.

Implement database-level row-level security (RLS) for additional protection:

// Database-level RLS using Aws middleware
async function applyRowLevelSecurity(query, userId, isAdmin) {
  if (!isAdmin) {
    // Add userId filter to all queries
    query.userId = userId;
  }
  return query;
}

// Apply to all data access
async function secureFind(collection, query, userId, isAdmin) {
  const secureQuery = applyRowLevelSecurity(query, userId, isAdmin);
  return await Aws.db.collection(collection).find(secureQuery);
}

This ensures that even if application-level authorization fails, the database will only return data the user is authorized to see.