Question 393 of 505

Application Deployment and Security →hardMultiple ChoiceObjective-mapped

200-901 Application Deployment and Security Practice Question

This 200-901 practice question tests your understanding of application deployment and security. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.

Exhibit

from flask import Flask, request, jsonify
import jwt

app = Flask(__name__)
app.config['SECRET_KEY'] = 'my-secret'

@app.route('/login', methods=['POST'])
def login():
    username = request.json.get('username')
    password = request.json.get('password')
    # Verify username/password (omitted)
    token = jwt.encode({'user': username}, app.config['SECRET_KEY'], algorithm='HS256')
    return jsonify({'token': token})

@app.route('/protected', methods=['GET'])
def protected():
    token = request.headers.get('Authorization')
    if not token:
        return jsonify({'msg': 'Missing token'}), 401
    try:
        # token format: "Bearer <token>"
        token = token.split()[1]
        data = jwt.decode(token, app.config['SECRET_KEY'], algorithms=['HS256'])
        return jsonify({'msg': 'Access granted', 'user': data['user']})
    except:
        return jsonify({'msg': 'Invalid token'}), 401

Refer to the exhibit. A security audit reveals that the authentication mechanism is vulnerable. Which attack is most likely possible?

Clue words in this question

Noticing these words before you look at the options changes how you read each choice.

Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

Question 1hardmultiple choice

Full question →

Exhibit

from flask import Flask, request, jsonify
import jwt

app = Flask(__name__)
app.config['SECRET_KEY'] = 'my-secret'

@app.route('/login', methods=['POST'])
def login():
    username = request.json.get('username')
    password = request.json.get('password')
    # Verify username/password (omitted)
    token = jwt.encode({'user': username}, app.config['SECRET_KEY'], algorithm='HS256')
    return jsonify({'token': token})

@app.route('/protected', methods=['GET'])
def protected():
    token = request.headers.get('Authorization')
    if not token:
        return jsonify({'msg': 'Missing token'}), 401
    try:
        # token format: "Bearer <token>"
        token = token.split()[1]
        data = jwt.decode(token, app.config['SECRET_KEY'], algorithms=['HS256'])
        return jsonify({'msg': 'Access granted', 'user': data['user']})
    except:
        return jsonify({'msg': 'Invalid token'}), 401

A
Cross-site scripting (XSS) via the token.
Why wrong: The token is not rendered in HTML; XSS is not indicated.
B
Token forgery if the secret key is weak.
The weak secret 'my-secret' can be easily guessed, allowing attacker to forge valid tokens.
C
Man-in-the-middle attack due to missing HTTPS.
Why wrong: While HTTPS is important, the exhibit does not show it missing, and the audit identified the secret key issue.
D
SQL injection through the login endpoint.
Why wrong: No SQL database interaction is shown; it's just a demonstration.

Full breakdown with real-world context →

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

✓

Token forgery if the secret key is weak.

The exhibit shows a JSON Web Token (JWT) being used for authentication. If the secret key used to sign the JWT is weak or easily guessable, an attacker can forge a valid token by brute-forcing the secret and then crafting a token with arbitrary claims (e.g., elevated privileges). This is a classic token forgery attack, not a cross-site scripting or injection attack, because the vulnerability lies in the signing mechanism, not in input handling or transport security.

Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✗
Cross-site scripting (XSS) via the token.
Why it's wrong here
The token is not rendered in HTML; XSS is not indicated.
✓
Token forgery if the secret key is weak.
Why this is correct
The weak secret 'my-secret' can be easily guessed, allowing attacker to forge valid tokens.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Man-in-the-middle attack due to missing HTTPS.
Why it's wrong here
While HTTPS is important, the exhibit does not show it missing, and the audit identified the secret key issue.
✗
SQL injection through the login endpoint.
Why it's wrong here
No SQL database interaction is shown; it's just a demonstration.

Common exam traps

Common exam trap: answer the scenario, not the keyword

Cisco often tests the distinction between attacks that target the authentication mechanism itself (like token forgery) versus attacks that exploit input handling (XSS, SQLi) or transport security (MITM), leading candidates to pick a wrong option because they focus on a general security flaw (e.g., missing HTTPS) rather than the specific vulnerability implied by the token's weak secret.

Trap categories for this question

Command / output trap
While HTTPS is important, the exhibit does not show it missing, and the audit identified the secret key issue.

Detailed technical explanation

How to think about this question

JWTs are typically signed using HMAC with SHA-256 (HS256) or RSA (RS256). If the secret key for HS256 is weak (e.g., 'secret' or a short dictionary word), an attacker can perform an offline brute-force attack using tools like hashcat or John the Ripper to recover the key. Once the key is known, the attacker can modify the JWT payload (e.g., changing 'role': 'user' to 'role': 'admin') and re-sign it, bypassing authentication entirely. This is distinct from XSS, which requires script injection, or MITM, which requires intercepting network traffic.

KKey Concepts to Remember

Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.

TExam Day Tips

Watch for words such as best, first, most likely and least administrative effort.
Review why wrong options are wrong, not only why the correct option is correct.

Key takeaway

Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Real-world example

How this comes up in practice

A junior network technician can log in to a core router but cannot reach the enable prompt or configuration mode. The AAA server is authenticating the login — but the authorisation policy only grants privilege level 1, not 15. Authentication (who you are) is working; authorisation (what you can do) is not.

What to study next

Got this wrong? Here's your next step.

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

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FAQ

Questions learners often ask

What does this 200-901 question test?

Application Deployment and Security — This question tests Application Deployment and Security — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: Token forgery if the secret key is weak. — The exhibit shows a JSON Web Token (JWT) being used for authentication. If the secret key used to sign the JWT is weak or easily guessable, an attacker can forge a valid token by brute-forcing the secret and then crafting a token with arbitrary claims (e.g., elevated privileges). This is a classic token forgery attack, not a cross-site scripting or injection attack, because the vulnerability lies in the signing mechanism, not in input handling or transport security.

What should I do if I get this 200-901 question wrong?

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

Are there clue words in this question I should notice?

Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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Last reviewed: Jun 24, 2026

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