Explore fundamental secure practices for local storage with this introductory quiz, designed to highlight safe data handling, encryption, access control, and threat prevention. Enhance your understanding of key security concepts related to client-side storage and data protection measures.
Which type of data should never be stored in plain text within local storage, such as usernames, passwords, or credit card details?
Explanation: Personal identification numbers and similar sensitive data should never be stored in plain text because it exposes users to theft if local storage is compromised. While daily login timestamps and user display color preferences are low-risk, storing them as plain text does not typically threaten user safety. Non-sensitive session flags might be present and are usually harmless when stored openly. Only sensitive information like personal identification numbers truly require strong protection.
Why is it important to clear or remove unnecessary local storage data when a user logs out of an application?
Explanation: Clearing local storage data upon logout helps prevent unauthorized users from accessing sensitive information left behind on the device. Saving device battery and increasing screen brightness are unrelated to data storage and are included only as distractions. Improving network signal is not affected by local storage practices. Security is the primary reason for removing data upon logout.
If you absolutely must store sensitive data on the client side, which security technique should you always use?
Explanation: Sensitive data should always be encrypted before it is stored locally to help protect it from unauthorized access. Minification and compression merely reduce file size and do not secure the data. Obfuscation only makes data harder to read but does not provide robust security. Encryption is the only option here that actually protects the data’s confidentiality.
Which statement best describes the common storage size limits for local storage in modern browsers?
Explanation: Modern browsers generally limit local storage to around 5 to 10 megabytes per origin to prevent excessive space usage. It does not support unlimited space; that would be a security risk. The 50 kilobyte limit is incorrect and much too small for most browsers. There is also no requirement for storage to match device memory.
What security threat can allow attackers to steal data from local storage via malicious scripts?
Explanation: Cross-Site Scripting (XSS) allows attackers to run unwanted scripts in a browser, potentially accessing local storage data. Denial of Service affects availability, not data theft. Man-in-the-Middle involves intercepting network traffic rather than client storage. Buffer Overflow is primarily a concern in low-level systems, not web local storage.
Who is able to access the data stored in browser local storage?
Explanation: Local storage is scoped per origin, so only scripts running from the same protocol, host, and port combination can access the data. Scripts from other websites or origins cannot read it due to browser security restrictions. Applications outside the browser do not automatically have access. Remote attackers cannot access local storage unless another vulnerability exists.
What is a safer alternative to storing authentication tokens in local storage?
Explanation: HTTP-only cookies provide better security for sensitive tokens because they cannot be accessed by JavaScript, helping prevent token theft. Saving tokens in plain text files or uploading them to public folders exposes them unnecessarily. Writing to the clipboard is insecure and temporary, not intended for sensitive data. Secure cookies are the recommended approach.
Which storage type persists data after the browser window is closed until it is explicitly deleted?
Explanation: Local storage retains data until it is manually cleared, persisting across browser sessions. Session storage only lasts until the tab or window is closed. Cache storage is used for files, not typically application data, and RAM buffers are cleared on close. Local storage is the correct answer for persistent client-side data.
When storing JSON data in local storage, what practice enhances security and stability?
Explanation: Sanitizing inputs ensures any data written to local storage is safe, reducing security risks such as injection attacks. Randomizing property names and using uppercase letters do not provide actual security or improve stability. Saving as XML may change the format but does not address input safety. Input sanitization is the essential step.
Unlike some storage types, what feature does local storage lack in managing how long data persists?
Explanation: Local storage does not support built-in expiration dates, so data remains until explicitly removed. While it only stores text data by default, that is not a managing feature. Storage is not based on device location, and local storage does not provide encryption by default. Built-in expiry is the feature it lacks.