The answer is setting runAsNonRoot: true, readOnlyRootFilesystem: true, and dropping all capabilities with drop: ['ALL']. This combination is most effective for Kubernetes pod security context to prevent container escape because it directly eliminates the three primary vectors attackers exploit: running as root grants full host access, a writable filesystem allows binary injection or kernel module loading, and default capabilities like CAP_SYS_ADMIN enable namespace escape. On the CompTIA SecurityX CAS-004 exam, this question tests your ability to apply least-privilege principles within a pod security context, often appearing as a multi-select scenario where distractors include privileged mode (which bypasses all restrictions) or leaving default capabilities intact. A common trap is confusing dropping all capabilities with running as non-root alone—both are needed. Memory tip: think “No root, no write, no caps” to recall the three pillars of container escape prevention.
CAS-004 Scripting, Containers and Automation Practice Question
This CAS-004 practice question tests your understanding of scripting, containers and automation. 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 security engineer is hardening a Kubernetes cluster. They want to reduce the risk of container escape attacks. Which combination of settings is most effective at the pod security context level?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Set runAsNonRoot: true, readOnlyRootFilesystem: true, and drop: ['ALL'].
Using read-only root filesystem and dropping all capabilities limits the attack surface. Option D is correct. Option A allows privileged access. Option B keeps default capabilities. Option C runs as root, increasing risk.
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.
✓
Set runAsNonRoot: true, readOnlyRootFilesystem: true, and drop: ['ALL'].
Why this is correct
Drops all capabilities, enforces non-root, and read-only filesystem – defense in depth against escapes.
Related concept
Authentication checks who the user is.
✗
Set runAsNonRoot: false and readOnlyRootFilesystem: true.
Why it's wrong here
Running as root with a read-only filesystem still permits kernel exploits.
✗
Set runAsUser: 1000 and capabilities.add: ['NET_ADMIN'].
Why it's wrong here
Adding capabilities expands the attack surface; NET_ADMIN can be exploited.
✗
Set privileged: true and readOnlyRootFilesystem: false.
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 small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Got this wrong? Here's your next step.
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related CAS-004 questions on access control and AAA configuration.
Scripting, Containers and Automation — This question tests Scripting, Containers and Automation — Authentication checks who the user is..
What is the correct answer to this question?
The correct answer is: Set runAsNonRoot: true, readOnlyRootFilesystem: true, and drop: ['ALL']. — Using read-only root filesystem and dropping all capabilities limits the attack surface. Option D is correct. Option A allows privileged access. Option B keeps default capabilities. Option C runs as root, increasing risk.
What should I do if I get this CAS-004 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 CAS-004 questions on access control and AAA configuration.
What is the key concept behind this question?
Authentication checks who the user is.
About these practice questions
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These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A security engineer is reviewing a Kubernetes deployment where the pod spec includes `securityContext: { privileged: true }`. What is the primary security concern of this configuration?
hard
A.The container can access host resources like the filesystem
B.The container can run as root
C.The container has unrestricted network access
✓ D.The container can modify the host's kernel
Why D: Privileged containers have almost all capabilities of the host, including access to host devices and kernel modules. This significantly increases the attack surface compared to running as root alone.
Variation 2. A security engineer is implementing container security controls. Which TWO practices are most effective in preventing privilege escalation within a container? (Choose two.)
medium
✓ A.Dropping all capabilities (CAP_DROP=ALL)
B.Enabling SELinux
C.Using host networking
D.Mounting /var/run/docker.sock
✓ E.Setting USER to non-root in the Dockerfile
Why A: Setting USER to non-root prevents the container from running as root, and dropping all capabilities removes many known escalation vectors. Using host networking and mounting the Docker socket increase risk. SELinux helps but is not specific to privilege escalation.
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Question Discussion
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