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Unauthorized access to files

Need​

Prevention of unauthorized access to files and functionalities

Context​

  • Usage of Swift for iOS and macOS app development
  • Usage of UIKit for building modern and responsive user interfaces
  • Usage of Alamofire for making network requests in iOS development

Description​

Non compliant code​

import UIKit
import Alamofire

class UpdateUserDataViewController: UIViewController {

    @IBOutlet weak var usernameTextField: UITextField!
    @IBOutlet weak var passwordTextField: UITextField!
    
    @IBAction func updateButtonTapped(_ sender: UIButton) {
        let parameters: Parameters = [
            "username": usernameTextField.text!,
            "password": passwordTextField.text!
        ]
        
        Alamofire.request("https://yoursharepoint.com/_api/web/lists/getbytitle('UserData')/items", method: .post, parameters: parameters, encoding: JSONEncoding.default)
            .responseJSON { response in
                print(response)
        }
    }
}

This vulnerable Swift code is for a mobile application running on iOS. The code is part of a view controller that handles the update of user data.

The vulnerability lies in the updateButtonTapped function, where it takes user inputs from usernameTextField and passwordTextField, and directly uses them as parameters in a POST request to a SharePoint site.

This is dangerous because it does not validate or sanitize the user input before using it in the request. A malicious user can input special characters or code into the text fields that could be interpreted by the server in unintended ways, leading to unauthorized access to files and functionalities.

For example, a user could potentially input a string that, when interpreted by the server, causes it to return all files in the SharePoint site, not just the ones the user is authorized to access. This is a serious security vulnerability known as an Injection attack, and in this case, specifically a SharePoint Injection attack.

Steps​

  • Implement proper input validation to prevent injection of potentially dangerous characters.
  • Use parameterized queries or prepared statements to securely handle user input.
  • Implement proper authentication and authorization mechanisms to restrict access to sensitive functionalities and files.
  • Regularly update and patch the application and its dependencies to address any known security vulnerabilities.
  • Implement secure coding practices, such as input sanitization and output encoding, to prevent common security vulnerabilities.
  • Conduct regular security assessments and penetration testing to identify and address any potential vulnerabilities.
  • Educate developers on secure coding practices and provide training on identifying and mitigating security vulnerabilities.

Compliant code​

import UIKit
import Alamofire

class UpdateUserDataViewController: UIViewController {

    @IBOutlet weak var usernameTextField: UITextField!
    @IBOutlet weak var passwordTextField: UITextField!
    
    @IBAction func updateButtonTapped(_ sender: UIButton) {
        guard let username = usernameTextField.text, let password = passwordTextField.text else {
            return
        }
        
        let parameters: Parameters = [
            "username": username,
            "password": password
        ]
        
        Alamofire.request("https://yoursharepoint.com/_api/web/lists/getbytitle('UserData')/items", method: .post, parameters: parameters, encoding: JSONEncoding.default)
            .validate() // Add validation to check the server's response
            .responseJSON { response in
                switch response.result {
                case .success:
                    print("Update successful")
                case .failure(let error):
                    print("Update failed: \\(error)")
                }
        }
    }
}

The updated code now includes proper input validation to prevent injection of potentially dangerous characters. The guard let statement ensures that the username and password are not nil before they are used to create the parameters dictionary. This prevents potential crashes from force unwrapping nil values.

The Alamofire request now includes a validate() function call. This function automatically validates the status code within the 200...299 range, and that the Content-Type header of the response matches the Accept header of the request, if one is provided. If either check fails, the .failure case of the result is returned.

This code also handles the response in a switch statement, checking for .success and .failure cases. This allows for better error handling and gives feedback if the update was successful or not.

Remember, this is just a part of the solution. You should also implement proper authentication and authorization mechanisms, regularly update and patch the application and its dependencies, implement secure coding practices, conduct regular security assessments and penetration testing, and educate developers on secure coding practices.

References​

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