Blog | G5 Cyber Security

React Conditional Rendering: User Control

G5 Cyber Security

TL;DR

Yes, an end-user can indirectly modify conditional rendering in React, but not by directly changing the code. They do this through data changes that trigger re-renders and different conditions being met. You need to design your components to handle these user-driven data updates securely.

How Users Affect Conditional Rendering

  1. Data Input: The most common way a user influences rendering is by providing input (e.g., forms, buttons, selections). This input changes the component’s state or props.
    • State Changes: When a user interacts with an element that updates state using setState, React re-renders the component. 
      this.setState({ showDetails: !this.state.showDetails });
    • Prop Updates: If data is passed from a parent component as props, changes in that parent’s data will also trigger a re-render.
  2. Conditional Logic: Your React components use conditional logic (if statements, ternary operators) based on this state or prop data to determine what is displayed. 
    {this.state.isLoading ? <LoadingSpinner /> : <Content />}
  3. User-Driven Conditions: The user’s input effectively changes the conditions evaluated by your component, leading to different parts of the UI being rendered.

Preventing Unintended Changes

  1. Input Validation: Always validate user input on both the client-side (React) and server-side. This prevents malicious or unexpected data from reaching your component.
    • Type Checking: Ensure the input is of the expected type (number, string, boolean).
    • Range Checks: If a number is expected, verify it falls within acceptable limits.
    • Sanitization: Clean potentially harmful characters from strings to prevent XSS attacks.
  2. Controlled Components: Use controlled components for form inputs. This means React manages the input’s value, and you handle updates through state changes. 
    <input type="text" value={this.state.inputValue} onChange={this.handleChange} />
  3. Immutable Data: Treat your state as immutable. Instead of directly modifying it, create new copies with the updated values. 
    this.setState({ ...this.state, inputValue: newValue });
  4. Secure API Calls: If user input is used in API calls, ensure your backend properly validates and sanitizes the data before processing it.
  5. Avoid Direct DOM Manipulation: Never directly manipulate the DOM. Let React handle updates based on state changes.

Example Scenario

Imagine a component that shows or hides a sensitive section based on whether a user has entered a correct password.

  1. The user types a password into an input field.
  2. React updates the component’s state with the typed password (using a controlled component).
  3. A conditional statement checks if the password matches the expected value. 
    {this.state.password === "secretPassword" ? <SensitiveSection /> : null}
  4. If the passwords match, the SensitiveSection is rendered; otherwise, it’s hidden.

In this case, the user controls whether the sensitive section is visible by providing input that changes the conditional rendering.

Exit mobile version