The answer is cross-site scripting (XSS) via uploaded file. This is correct because the tester exploited a misconfigured S3 bucket with public write access—specifically the s3:PutObject permission—to upload a malicious JavaScript file that steals cookies. When other users access that file in the bucket, the script executes in their browsers, making it a classic storage-based XSS attack where the attacker’s payload is hosted on a trusted cloud domain. On the Certified Ethical Hacker CEH exam, this scenario tests your understanding of cloud-specific attack vectors, often appearing in the cloud penetration testing domain; a common trap is confusing it with a server-side attack like file inclusion, but the key distinction is that XSS is client-side and relies on user interaction with the uploaded file. Remember the memory tip: “PutObject for XSS” links the S3 write permission directly to the client-side payload delivery.
CEH Practice Question: Advanced Topics: Wireless, Cloud, IoT, Cryptography
This CEH practice question tests your understanding of advanced topics: wireless, cloud, iot, cryptography. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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.
During a cloud penetration test, a tester discovers an AWS S3 bucket that allows public 's3:PutObject' access. The tester uploads a file containing JavaScript that steals cookies. Which type of attack is this an example of?
The tester uploaded JavaScript to a public S3 bucket. When users browse the bucket or link to the file, the script executes in their browser, stealing cookies.
B
Server-Side Request Forgery (SSRF)
Why wrong: SSRF tricks the server into making requests; here the attack is client-side via uploaded file.
C
Insecure Direct Object Reference (IDOR)
Why wrong: IDOR accesses unauthorized resources via predictable identifiers; here the bucket is public and the attack is content-based.
D
S3 bucket privilege escalation
Why wrong: Privilege escalation would involve gaining higher AWS permissions, not serving malicious content.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Cross-Site Scripting (XSS) via uploaded file
Uploading malicious content to an S3 bucket with public write access enables storage of attacker-controlled files. When users access these files, a client-side attack (like XSS) can occur. This is a classic example of a storage-based attack via misconfigured S3 bucket.
Key principle: Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
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 uploaded file
Why this is correct
The tester uploaded JavaScript to a public S3 bucket. When users browse the bucket or link to the file, the script executes in their browser, stealing cookies.
Related concept
Authentication checks who the user is.
✗
Server-Side Request Forgery (SSRF)
Why it's wrong here
SSRF tricks the server into making requests; here the attack is client-side via uploaded file.
✗
Insecure Direct Object Reference (IDOR)
Why it's wrong here
IDOR accesses unauthorized resources via predictable identifiers; here the bucket is public and the attack is content-based.
✗
S3 bucket privilege escalation
Why it's wrong here
Privilege escalation would involve gaining higher AWS permissions, not serving malicious content.
Common exam traps
Common exam trap: authentication is not authorization
Logging in proves the user can authenticate. It does not automatically mean the user is allowed to enter privileged or configuration mode. Watch for AAA authorization, privilege level and command authorization details.
Detailed technical explanation
How to think about this question
This kind of question is testing the difference between identity and permission. A user may successfully log in to a router because authentication is working, but still fail to enter configuration mode because authorization is missing, misconfigured or mapped to a lower privilege level.
KKey Concepts to Remember
Authentication checks who the user is.
Authorization controls what the user is allowed to do after login.
Privilege levels affect access to EXEC and configuration commands.
AAA, TACACS+ and RADIUS can separate login success from command access.
TExam Day Tips
→Do not assume successful login means full administrative access.
→Look for words such as cannot enter configuration mode, privilege level, authorization or command access.
→Separate login problems from permission problems before choosing the answer.
Key takeaway
Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CEH question in full detail.
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related CEH questions on access control and AAA configuration.
Advanced Topics: Wireless, Cloud, IoT, Cryptography — This question tests Advanced Topics: Wireless, Cloud, IoT, Cryptography — Authentication checks who the user is..
What is the correct answer to this question?
The correct answer is: Cross-Site Scripting (XSS) via uploaded file — Uploading malicious content to an S3 bucket with public write access enables storage of attacker-controlled files. When users access these files, a client-side attack (like XSS) can occur. This is a classic example of a storage-based attack via misconfigured S3 bucket.
What should I do if I get this CEH question wrong?
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related CEH questions on access control and AAA configuration.
What is the key concept behind this question?
Authentication checks who the user is.
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