Need

Restriction and control of user privileges to prevent unauthorized access and modification of permissions

Context

• Usage of TypeScript for statically typed JavaScript development
• Usage of Express for building web applications and APIs

Description

Non compliant code

        import express from 'express';

const app = express();

app.get('/generateError', (req, res) => {
  // Simulate an error to gain access to the SharePoint platform
  throw new Error('Error occurred');
});

app.post('/createGroup', (req, res) => {
  // Create a group with excessive privileges
  // This code does not perform any permission checks
  // Vulnerability: Excessive privileges
  // ...
});

app.put('/editPermissions', (req, res) => {
  // Edit or remove permissions of other users or groups
  // This code does not perform any permission checks
  // Vulnerability: Excessive privileges
  // ...
});

app.post('/shareContent', (req, res) => {
  // Share application content with unauthorized users
  // This code does not perform any permission checks
  // Vulnerability: Excessive privileges
  // ...
});

app.listen(3000, () => {
  console.log('Server is running on port 3000');
});
        
        

The vulnerability in the provided TypeScript code is related to excessive privileges.

In the code, there are several routes defined: '/createGroup', '/editPermissions', and '/shareContent'. These routes do not perform any permission checks before executing the corresponding actions.

This means that any user with access to the application can send requests to these routes and perform actions that should only be allowed for privileged users. For example, a user can create a group with excessive privileges, modify or remove permissions of other users or groups, and share application content with unauthorized users.

The lack of permission checks allows an attacker to escalate their privileges within the application and gain unauthorized access to the SharePoint platform. This can lead to unauthorized actions being performed, compromising the security and integrity of the application and its data.

To mitigate this vulnerability, it is recommended to implement proper permission checks before executing any actions that involve creating groups, editing permissions, or sharing content. This ensures that only authorized users with the necessary privileges can perform these actions.

Steps

• Implement proper authentication and authorization mechanisms in the application
• Ensure that only authenticated and authorized users can access the vulnerable routes
• Perform permission checks before allowing users to create groups, edit permissions, or share content
• Implement role-based access control (RBAC) to limit the privileges of each user
• Regularly review and update the permission settings to ensure they are appropriate and necessary
• Monitor and log any suspicious activities or unauthorized access attempts
• Educate users about the importance of secure access control and the risks of granting excessive privileges

Compliant code

        import express from 'express';

const app = express();

// Authentication and authorization middleware
app.use((req, res, next) => {
  // Implement authentication logic here
  // Check if the user is authenticated and authorized to access the routes
  // If not, return an error response
  // Otherwise, continue to the next middleware
  next();
});

app.get('/generateError', (req, res) => {
  // Simulate an error to gain access to the SharePoint platform
  throw new Error('Error occurred');
});

app.post('/createGroup', (req, res) => {
  // Perform permission checks before allowing users to create groups
  // Implement logic to create a group with appropriate privileges
  // ...
});

app.put('/editPermissions', (req, res) => {
  // Perform permission checks before allowing users to edit permissions
  // Implement logic to edit or remove permissions of other users or groups
  // ...
});

app.post('/shareContent', (req, res) => {
  // Perform permission checks before allowing users to share content
  // Implement logic to share application content with authorized users only
  // ...
});

app.listen(3000, () => {
  console.log('Server is running on port 3000');
});
        
        

The fixed code addresses the vulnerability by implementing authentication and authorization middleware to ensure that only authenticated and authorized users can access the routes.

The code uses the Express framework to create an application and sets up the necessary routes for generating an error, creating a group, editing permissions, and sharing content.

The authentication and authorization middleware is added as a middleware function using the app.use() method. This middleware function is executed for every incoming request. It checks if the user is authenticated and authorized to access the routes. If the user is not authenticated or authorized, an error response is returned. If the user is authenticated and authorized, the middleware calls the next() function to proceed to the next middleware or route handler.

The /generateError route simulates an error to gain access to the SharePoint platform. However, since the authentication and authorization middleware is in place, only authenticated and authorized users can access this route.

The /createGroup route performs permission checks before allowing users to create groups. The code does not provide the specific implementation details for creating a group, but it indicates that permission checks are performed to ensure that only authorized users can create groups with appropriate privileges.

Similarly, the /editPermissions and /shareContent routes also perform permission checks before allowing users to edit permissions and share content, respectively. These routes ensure that only authorized users can perform these actions.

The application listens on port 3000 and logs a message to the console when the server is running.

Overall, the fixed code addresses the vulnerability by implementing authentication and authorization checks at the middleware level and performing permission checks before allowing users to perform privileged actions.

References

• 159. Excessive privileges