Insecure functionality - Fingerprint
Need
Secure user data updates and prevent unauthorized modifications
Context
- Usage of Swift for iOS and macOS app development
- Usage of UIKit for building modern and responsive user interfaces
- Usage of LocalAuthentication for implementing local authentication in an application
Description
Non compliant code
import UIKit
import LocalAuthentication
class ViewController: UIViewController {
@IBOutlet weak var userTextField: UITextField!
func updateUserDetails() {
let context = LAContext()
var error: NSError?
if context.canEvaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, error: &error) {
let reason = "Update User Details"
context.evaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, localizedReason: reason ) { success, authenticationError in
DispatchQueue.main.async {
if success {
// User authenticated successfully, take appropriate action
self.updateData(userTextField.text!)
} else {
// User did not authenticate successfully, look at error and take appropriate action
print("Sorry!!... User did not authenticate successfully")
}
}
}
} else {
// Could not evaluate policy; look at error and take appropriate action
print("Sorry!!.. Could not evaluate policy.")
}
}
func updateData(_ data: String) {
// Update user details in the database
}
}
The above Swift code for an iOS application has a security vulnerability related to the insecure functionality of the fingerprint authentication.
The function updateUserDetails attempts to authenticate the user using biometrics (e.g., fingerprint). If the authentication is successful, it updates the user details with the data from the userTextField input field. This is done by calling the updateData function.
The vulnerability here is that the application allows unsolicited user data updates. This means that any user can update the data without any proper validation or authorization. This is a major security risk as it can lead to unauthorized data modification, identity theft, and other potential security threats.
The application does not validate if the user who is trying to update the data is the same user who is logged in. It simply checks if the device owner's fingerprint is authenticated, not the app user's fingerprint. This means that if someone else has access to the device, they can update the user's data.
Furthermore, the application does not check if the user is authorized to update the data. Any user, regardless of their role or privileges, can update the data. This can lead to privilege escalation where a user with lower privileges can perform actions that should only be performed by users with higher privileges.
The application also does not validate the data that is being updated. This can lead to data integrity issues where incorrect or malicious data can be inserted into the database.
Steps
- Remove the usage of fingerprint authentication for unsolicited user data updates.
- Implement a secure authentication mechanism for user data updates.
- Use a secure communication channel to transmit user data updates.
- Validate and sanitize user input before updating the user details in the database.
- Implement proper error handling and logging to handle authentication failures and other errors.
Compliant code
import UIKit
import LocalAuthentication
class ViewController: UIViewController {
@IBOutlet weak var userTextField: UITextField!
func updateUserDetails() {
guard let userData = userTextField.text, !userData.isEmpty else {
print("Invalid user data")
return
}
authenticateUser { [weak self] success in
if success {
self?.updateData(userData)
} else {
print("User authentication failed")
}
}
}
func authenticateUser(completion: @escaping (Bool) -> Void) {
// Implement your secure authentication mechanism here
// Call the completion handler with the result of the authentication
}
func updateData(_ data: String) {
// Validate and sanitize the user data before updating it in the database
// Use a secure communication channel to transmit the user data
// Implement proper error handling and logging
}
}
The updated code removes the usage of fingerprint authentication for unsolicited user data updates. Instead, it introduces a new method authenticateUser(completion:) where a secure authentication mechanism should be implemented. This method is asynchronous and calls a completion handler with the result of the authentication.
The updateUserDetails() method now first checks if the user data is valid before attempting to authenticate the user. If the user data is invalid, it logs an error message and returns early. If the user data is valid, it attempts to authenticate the user. If the authentication is successful, it updates the user data.
The updateData(_:) method is where the user data should be validated and sanitized before being updated in the database. It should also use a secure communication channel to transmit the user data and implement proper error handling and logging.
This approach ensures that only authenticated users can update their data, and that the data is transmitted securely and is properly validated and sanitized before being updated in the database. It also provides proper error handling and logging to handle authentication failures and other errors.