The correct answer is cron jobs, SSH authorized_keys, and systemd services, as these three represent the most common Linux persistence mechanisms encountered in forensic analysis. Attackers leverage cron jobs to schedule malicious scripts at defined intervals, use SSH authorized_keys to maintain backdoor access via public key authentication, and create systemd service units to ensure malware restarts automatically after a reboot. On the Computer Hacking Forensic Investigator CHFI exam, this question tests your ability to distinguish between true persistence methods and standard system configuration files, with /etc/passwd often appearing as a distractor since it stores user accounts but does not trigger automatic execution. A common trap is confusing .bashrc with a primary persistence vector, though it only affects interactive shell sessions and is less reliable for attackers. To remember the three core mechanisms, think of the mnemonic “CSS” for Cron, SSH keys, and Systemd services.
CHFI OS and Network Forensics Practice Question
This CHFI practice question tests your understanding of os and network forensics. 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 persistence mechanisms found in Linux systems? (Select three.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
SSH authorized_keys
Cron jobs, SSH authorized_keys, and systemd services are common methods used by attackers to maintain persistence on Linux. /etc/passwd is for user accounts, not persistence. .bashrc runs for interactive shells, but it is less common for persistence.
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.
✗
.bashrc in user home directories
Why it's wrong here
.bashrc runs when a user opens a terminal; it can be used but is less common for persistent access.
✓
SSH authorized_keys
Why this is correct
Adding an attacker's public key to authorized_keys allows persistent SSH access.
Related concept
Read the scenario before looking for a memorised answer.
✓
Systemd services (.service files)
Why this is correct
Systemd services can be created to start automatically at boot.
Related concept
Read the scenario before looking for a memorised answer.
✓
Cron jobs (crontab)
Why this is correct
Cron jobs can be scheduled to run malicious scripts at intervals.
Related concept
Read the scenario before looking for a memorised answer.
✗
/etc/passwd file modification
Why it's wrong here
Modifying /etc/passwd can create accounts, but it is not a typical stealthy persistence mechanism and is easily detected.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→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 practitioner preparing for the CHFI exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CHFI question in full detail.
Identify which CHFI exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
OS and Network Forensics — This question tests OS and Network Forensics — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: SSH authorized_keys — Cron jobs, SSH authorized_keys, and systemd services are common methods used by attackers to maintain persistence on Linux. /etc/passwd is for user accounts, not persistence. .bashrc runs for interactive shells, but it is less common for persistence.
What should I do if I get this CHFI question wrong?
Identify which CHFI exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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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