The correct mitigations are enabling AES-128 encryption in the Zigbee security suite and configuring MQTT to use TLS 1.2 with mutual authentication. Zigbee’s built-in security suite uses AES-128 to encrypt over-the-air frames, directly preventing eavesdropping on sensor IDs and values from unencrypted frames. For MQTT over Wi-Fi, TLS 1.2 with mutual authentication encrypts the payload and verifies both broker and client identities, stopping man-in-the-middle attacks. On the CEH exam, this question tests your understanding of IoT protocol weaknesses and layered encryption—a common trap is to recommend disabling Zigbee encryption or only using TLS on MQTT without mutual auth. Remember: Zigbee frames need AES-128 enabled at the network layer, while MQTT needs TLS at the transport layer. A useful mnemonic is “Zigbee locks the air, MQTT locks the wire”—both must be encrypted independently to secure smart building traffic.
CEH Wireless, IoT and Cloud Security Practice Question
This CEH practice question tests your understanding of wireless, iot and cloud 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.
A penetration tester is assessing the security of a smart building's IoT infrastructure. The building uses Zigbee sensors for temperature and motion detection, and some devices communicate using MQTT over Wi-Fi. During the assessment, the tester captures traffic and notices that some Zigbee devices are sending unencrypted frames containing sensor IDs and values. Which TWO actions should the tester recommend to mitigate the identified vulnerabilities? (Choose two.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enable Zigbee security suite (AES-128 encryption) on all sensor devices.
Option A is correct because Zigbee's security suite uses AES-128 encryption to protect over-the-air frames, preventing eavesdropping on sensor IDs and values. Enabling this suite ensures that captured unencrypted frames are no longer readable, directly mitigating the observed vulnerability. Option B is correct because MQTT over Wi-Fi without TLS exposes all communication in plaintext; configuring TLS 1.2 with mutual authentication encrypts the payload and verifies both broker and client identities, preventing man-in-the-middle attacks.
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.
✓
Enable Zigbee security suite (AES-128 encryption) on all sensor devices.
Why this is correct
Zigbee supports encryption; enabling it protects data in transit.
Related concept
Read the scenario before looking for a memorised answer.
✓
Configure MQTT to use TLS 1.2 with mutual authentication between brokers and clients.
Read the scenario before looking for a memorised answer.
✗
Disable encryption on MQTT to reduce latency and improve performance.
Why it's wrong here
Disabling encryption increases vulnerability.
✗
Implement device authentication using pre-shared keys only for Zigbee devices.
Why it's wrong here
Authentication alone does not encrypt the payload.
✗
Segment the IoT devices into a separate VLAN and restrict access with ACLs.
Why it's wrong here
Segmentation limits exposure but does not encrypt the data.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse network segmentation (VLANs) with data encryption, thinking that isolating IoT devices on a separate VLAN alone protects the confidentiality of unencrypted wireless frames.
Detailed technical explanation
How to think about this question
Zigbee's security suite uses AES-128-CCM* (a variant of CCM) for both encryption and integrity, with a frame counter to prevent replay attacks. MQTT over TLS 1.2 uses the TLS handshake to negotiate a session key, and mutual authentication requires both the broker and client to present valid X.509 certificates, which is critical in IoT to prevent rogue devices from connecting. In real-world smart buildings, unencrypted Zigbee traffic can be captured with a simple USB dongle and tools like Wireshark or KillerBee, exposing sensor data and enabling device spoofing.
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 help-desk technician troubleshoots why a newly connected PC cannot reach shared printers on the same floor. The cable is good, the switch port is active, but the PC is in VLAN 20 and the printers are in VLAN 10. The uplink trunk only allows VLAN 10. A trunk being up does not mean every VLAN crosses it.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CEH question in full detail.
Wireless, IoT and Cloud Security — This question tests Wireless, IoT and Cloud Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Enable Zigbee security suite (AES-128 encryption) on all sensor devices. — Option A is correct because Zigbee's security suite uses AES-128 encryption to protect over-the-air frames, preventing eavesdropping on sensor IDs and values. Enabling this suite ensures that captured unencrypted frames are no longer readable, directly mitigating the observed vulnerability. Option B is correct because MQTT over Wi-Fi without TLS exposes all communication in plaintext; configuring TLS 1.2 with mutual authentication encrypts the payload and verifies both broker and client identities, preventing man-in-the-middle attacks.
What should I do if I get this CEH question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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