The answer is hardcoded credentials, unencrypted communications, and insecure firmware updates. Hardcoded credentials are a critical IoT device vulnerability because manufacturers often embed static usernames and passwords—like 'admin/admin'—directly into device firmware for ease of deployment, which attackers can exploit via SSH, Telnet, or web interfaces to gain unauthorized access, as famously demonstrated in the Mirai botnet attacks. This violates the principle of least privilege and secure credential management. On the CompTIA SecurityX CAS-004 exam, this question tests your ability to identify common IoT security risks within the broader domain of embedded system threats; a common trap is confusing hardcoded credentials with weak encryption, but remember that hardcoded credentials are about static, unchangeable access, not data-in-transit protection. For a memory tip, think "HUF" for Hardcoded, Unencrypted, Firmware—the three pillars of IoT exposure.
CAS-004 Security Engineering Practice Question
This CAS-004 practice question tests your understanding of security engineering. 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.
Which THREE of the following are common vulnerabilities in IoT devices? (Select THREE.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Hardcoded credentials
Hardcoded credentials (Option B) are a common IoT vulnerability because manufacturers often embed default usernames and passwords (e.g., 'admin/admin') into device firmware for ease of deployment. Attackers can exploit these static credentials via SSH, Telnet, or web interfaces to gain unauthorized access, as seen in Mirai botnet attacks. This violates the principle of least privilege and secure credential management.
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.
✗
Large storage capacity
Why it's wrong here
IoT devices generally have limited storage, not large.
✓
Hardcoded credentials
Why this is correct
Many IoT devices ship with default or hardcoded credentials that cannot be changed.
Related concept
Read the scenario before looking for a memorised answer.
✓
Lack of secure boot
Why this is correct
Without secure boot, attackers can load malicious firmware.
Related concept
Read the scenario before looking for a memorised answer.
✗
High compute power
Why it's wrong here
IoT devices typically have low compute power.
✓
Unencrypted communications
Why this is correct
Many IoT devices transmit data without encryption, making it susceptible to interception.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CompTIA often tests the misconception that hardware features like storage or compute power are vulnerabilities, when in fact the risks stem from insecure design choices (e.g., hardcoded credentials, lack of encryption) rather than raw capability.
Detailed technical explanation
How to think about this question
Lack of secure boot (Option C) allows an attacker to replace the bootloader or kernel with malicious code, bypassing integrity checks. Unencrypted communications (Option E) expose data in transit over protocols like MQTT or CoAP, enabling eavesdropping or man-in-the-middle attacks. In practice, many IoT devices use plaintext HTTP or unencrypted MQTT (port 1883) due to resource constraints, making them trivial to intercept with tools like Wireshark.
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.
Security Engineering — This question tests Security Engineering — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Hardcoded credentials — Hardcoded credentials (Option B) are a common IoT vulnerability because manufacturers often embed default usernames and passwords (e.g., 'admin/admin') into device firmware for ease of deployment. Attackers can exploit these static credentials via SSH, Telnet, or web interfaces to gain unauthorized access, as seen in Mirai botnet attacks. This violates the principle of least privilege and secure credential management.
What should I do if I get this CAS-004 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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Question Discussion
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