The correct answer is the account lockout policy, because it failed to prevent the unauthorized privilege escalation. An account lockout policy is designed solely to thwart brute-force attacks by disabling an account after a set number of failed logins, but it does nothing to restrict what an authenticated user can do once inside the system. In this scenario, the attacker already had valid credentials, so the lockout mechanism was irrelevant; the escalation occurred through other means, such as exploiting a misconfigured sudoers file or a kernel vulnerability. On the Systems Security Certified Practitioner SSCP exam, this question tests your understanding that access control mechanisms have distinct scopes—lockout policies govern authentication, not authorization. A common trap is assuming lockout policies protect against all unauthorized access, but they only address login attempts. Remember the memory tip: “Lockout locks the door, but it doesn’t guard the keys inside.”
SSCP Access Controls Practice Question
This SSCP practice question tests your understanding of access controls. 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.
Exhibit
Refer to the exhibit. The following is from /var/log/secure on a Linux server:
Jan 21 09:15:30 server sshd[1234]: Failed password for invalid user admin from 192.168.1.1 port 22 ssh2
Jan 21 09:15:31 server sshd[1235]: Failed password for invalid user root from 192.168.1.1 port 22 ssh2
... (multiple similar lines)
Jan 21 09:20:01 server su[5678]: pam_unix(su:session): session opened for user root by john(uid=1000)
The failed attempts are all from the same IP, and then user 'john' successfully runs `su` to root.
Which access control mechanism most likely failed to prevent this unauthorized privilege escalation?
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.
Refer to the exhibit. The following is from /var/log/secure on a Linux server:
Jan 21 09:15:30 server sshd[1234]: Failed password for invalid user admin from 192.168.1.1 port 22 ssh2
Jan 21 09:15:31 server sshd[1235]: Failed password for invalid user root from 192.168.1.1 port 22 ssh2
... (multiple similar lines)
Jan 21 09:20:01 server su[5678]: pam_unix(su:session): session opened for user root by john(uid=1000)
The failed attempts are all from the same IP, and then user 'john' successfully runs `su` to root.
A
Sudoers configuration
Why wrong: Sudoers controls who can run commands as other users; it would not have prevented the su attempt if the password was guessed.
B
Account lockout policy
An account lockout policy would have locked the account after a threshold of failed attempts, preventing the eventual successful login.
C
Password policy
Why wrong: Password policy governs complexity and expiration, not the number of attempts.
D
SELinux
Why wrong: SELinux enforces mandatory access controls on processes, not authentication attempt limits.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Account lockout policy
An account lockout policy is designed to prevent brute-force attacks by locking an account after a specified number of failed login attempts. In the context of unauthorized privilege escalation, a lockout policy would not prevent a user who already has valid credentials from escalating privileges through other means, such as exploiting a misconfigured sudoers file or a kernel vulnerability. Therefore, the failure of the account lockout policy is the most likely mechanism that allowed the escalation, as it does not control what an authenticated user can do after login.
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.
✗
Sudoers configuration
Why it's wrong here
Sudoers controls who can run commands as other users; it would not have prevented the su attempt if the password was guessed.
✓
Account lockout policy
Why this is correct
An account lockout policy would have locked the account after a threshold of failed attempts, preventing the eventual successful login.
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.
✗
Password policy
Why it's wrong here
Password policy governs complexity and expiration, not the number of attempts.
✗
SELinux
Why it's wrong here
SELinux enforces mandatory access controls on processes, not authentication attempt limits.
Common exam traps
Common exam trap: answer the scenario, not the keyword
ISC2 often tests the misconception that account lockout policies are a catch-all defense against unauthorized access, when in fact they only prevent brute-force login attempts and do not control actions taken by an already authenticated user.
Trap categories for this question
Command / output trap
Sudoers controls who can run commands as other users; it would not have prevented the su attempt if the password was guessed.
Detailed technical explanation
How to think about this question
Account lockout policies are typically implemented via PAM (Pluggable Authentication Modules) on Linux/Unix systems, using modules like pam_tally2 or pam_faillock, which track failed login attempts in a file (e.g., /var/log/faillog) and lock the account after a threshold (commonly 3-5 attempts). However, once a user is authenticated, these modules have no control over subsequent actions, such as using sudo or exploiting SUID binaries. In real-world scenarios, an attacker who has compromised a user's password but is locked out due to failed attempts would simply wait for the lockout period to expire or use another account, making the lockout policy ineffective against privilege escalation that occurs after successful login.
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 security team runs a vulnerability scan on a web application and discovers an unpatched SQL injection flaw. The team prioritises remediation by CVSS score — critical flaws are patched within 24 hours, high within 7 days. Questions like this test whether you understand vulnerability management processes, scanning tools, and remediation prioritisation.
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.
Access Controls — This question tests Access Controls — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Account lockout policy — An account lockout policy is designed to prevent brute-force attacks by locking an account after a specified number of failed login attempts. In the context of unauthorized privilege escalation, a lockout policy would not prevent a user who already has valid credentials from escalating privileges through other means, such as exploiting a misconfigured sudoers file or a kernel vulnerability. Therefore, the failure of the account lockout policy is the most likely mechanism that allowed the escalation, as it does not control what an authenticated user can do after login.
What should I do if I get this SSCP 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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Question Discussion
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