Understanding Common Authentication Vulnerabilities: Replay, CSRF, and MITM Quiz

Assess your knowledge of authentication vulnerabilities including replay attacks, cross-site request forgery (CSRF), and man-in-the-middle (MITM) threats. This quiz covers core concepts, typical attack scenarios, and security measures related to modern authentication processes and web application security.

1. Replay Attacks and Token Reuse

   What happens in a replay attack when an attacker captures and resends a valid authentication token?

   1. The attacker must first decrypt the token to use it.
   2. The attacker modifies the token to change the user's password.
   3. The server automatically blocks the attack by changing its URL.
   4. The attacker can gain unauthorized access using a previously valid token.

   Explanation: In a replay attack, an attacker intercepts and resends a valid token or authentication message to impersonate a user and gain access. Unlike modifying the token, the attacker simply reuses the captured data. The server does not automatically block such attempts unless additional protection is in place. Decryption is not always necessary if the token is not properly protected.

2. Purpose of CSRF Tokens

   Why are anti-CSRF tokens used in web applications to prevent attacks?

   1. They block bots from crawling the website.
   2. They ensure any submitted request comes from the legitimate site by verifying a token.
   3. They prevent users from forgetting their passwords.
   4. They make the web page load faster by caching forms.

   Explanation: Anti-CSRF tokens are random values tied to a user's session and checked with each request, preventing unauthorized actions from external sites. Blocking bots and password management are unrelated to CSRF tokens. Caching is about performance and does not prevent CSRF attacks.

3. Identifying a Man-in-the-Middle Scenario

   If a cybercriminal intercepts communication by sitting between a user and a website, which vulnerability are they exploiting?

   1. Man-in-the-middle (MITM)
   2. SQL injection
   3. Password spraying
   4. Cross-site scripting (XSS)

   Explanation: MITM attacks involve an attacker intercepting or altering communication between two parties, often without their knowledge. XSS and SQL injection involve injecting malicious code or queries, not intercepting communication. Password spraying targets login attempts with common passwords, not interception.

4. Best Practice to Prevent Replay Attacks

   Which method helps prevent replay attacks by ensuring each authentication message is unique?

   1. Relying only on challenge questions
   2. Disabling cookies entirely
   3. Choosing longer passwords
   4. Using a unique nonce or timestamp with each authentication request

   Explanation: A nonce or timestamp ensures messages cannot be reused because they expire after a certain period or are valid only once. Disabling cookies is not a solution for replay attacks and can harm user experience. Longer passwords and challenge questions improve security but do not directly address replay messages.

5. Recognizing Cross-Site Request Forgery

   Which of the following is an example of a CSRF attack?

   1. A malicious user uploads a virus disguised as an image file.
   2. An attacker tricks a user into clicking a link that changes their account email without their knowledge.
   3. A hacker guesses a weak user password by repeatedly trying different combinations.
   4. A harmful JavaScript is injected to steal cookies from a user's browser.

   Explanation: CSRF attacks involve performing unwanted actions on behalf of authenticated users, such as changing account settings, without their consent. Password guessing is brute force, script injection is XSS, and uploading malware is a different security issue.

6. Common Consequence of a MITM Attack

   What is a likely result if a man-in-the-middle attack is successful during a user's login session?

   1. The attacker will crash the user's web browser.
   2. The attacker will automatically install applications on the server.
   3. The attacker could capture login credentials and impersonate the user.
   4. The attack will generate fake error messages for the user.

   Explanation: A successful MITM attack can allow the attacker to see or alter sensitive information, like usernames and passwords, leading to account compromise. Crashing the browser, generating errors, or installing apps on the server is not typical of MITM attacks.

7. CSRF Attack Prerequisite

   Which condition typically must be true for a CSRF attack to succeed against a target user?

   1. The user must use an outdated browser version.
   2. The website must use multi-factor authentication.
   3. The user must be currently authenticated on the target website.
   4. The attacker must know the user's password.

   Explanation: CSRF attacks work when the victim is already logged in on the targeted site because the attack relies on transferring the user's credentials in ongoing sessions. Attacker knowledge of the user's password is unnecessary, and multi-factor authentication typically helps prevent such attacks. The browser version is not a requirement.

8. Protection Against MITM Attacks

   Which protocol is commonly used to protect login data from man-in-the-middle interception?

   1. IMAP
   2. FTP
   3. SMTP
   4. HTTPS

   Explanation: HTTPS uses encryption to secure data transmitted between users and websites, making interception and misuse more difficult. FTP, SMTP, and IMAP are protocols used for file transfer and email that do not typically encrypt all traffic unless specifically configured.

9. Difference Between Replay and MITM Attacks

   How does a replay attack fundamentally differ from a man-in-the-middle attack?

   1. Replay attacks always use phishing emails; MITM attacks never do.
   2. Replay attacks target password storage; MITM attacks target email servers.
   3. Replay attacks depend on browser vulnerabilities; MITM attacks require malware.
   4. Replay attacks reuse captured data; MITM attacks actively intercept and possibly alter communication.

   Explanation: Replay attacks focus on resending valid, captured information without modification, while MITM attacks involve real-time interception and possible modification of messages. Browser vulnerabilities and malware are not exclusive requirements. The other two options do not accurately describe the attacks' differences.

10. Simple Step to Mitigate CSRF

    What is a straightforward way for developers to reduce the risk of CSRF in their web forms?

    1. Ban the use of browser autofill for forms.
    2. Require passwords to be at least 12 characters.
    3. Include a server-generated hidden CSRF token in each form submission.
    4. Force a time delay before form submission.

    Explanation: Adding a unique CSRF token to each form makes it difficult for attackers to forge authenticated requests. Longer passwords and blocking autofill do not stop CSRF. Forcing delays may inconvenience users without addressing the attack.