GCIH Incident Response and Cyber Investigation Practice Question
An incident responder is analyzing a compromised Linux server. The attacker gained access via SSH and escalated privileges. The responder wants to identify persistence mechanisms. Which TWO of the following locations should the responder examine? (Choose two.)
⚠ Common exam trap
Watch out — candidates often confuse log files or common configuration files like /etc/passwd with actual persistence mechanisms, when persistence requires a mechanism that automatically re-establishes access.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
User's ~/.ssh/authorized_keys file
The two most common Linux persistence mechanisms are cron jobs and SSH authorized_keys. Cron jobs allow scheduled execution of malicious code, while authorized_keys enables passwordless SSH access. Both are frequently used by attackers to maintain a foothold. The auth.log, /etc/hosts, and /etc/passwd are not persistence mechanisms; they serve other purposes and may be modified for different attack goals.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
User's ~/.ssh/authorized_keys file
Why this is correct
The authorized_keys file contains public keys that are allowed to log in without a password. Attackers often add their own public key to maintain SSH access. Checking this file for unauthorized keys is a critical step in identifying persistence on a compromised Linux system.
- ✗
/etc/hosts
Why it's wrong here
The /etc/hosts file maps hostnames to IP addresses. While attackers might modify it to redirect traffic, it is not a typical persistence mechanism. It does not execute code or provide ongoing access. It is more often used for man-in-the-middle attacks or to block security updates.
- ✗
/etc/passwd
Why it's wrong here
The /etc/passwd file contains user account information. Attackers may add a new user with a UID of 0 to gain root access, but this is a form of account creation, not a persistence mechanism that runs automatically. It is worth checking, but it is less common than cron jobs or SSH keys for maintaining access.
- ✓
/etc/crontab and /etc/cron.* directories
Why this is correct
Cron jobs are a common persistence mechanism on Linux. Attackers can add entries to /etc/crontab or place scripts in /etc/cron.d, /etc/cron.hourly, etc., to execute malicious code periodically. Examining these locations is essential to detect scheduled tasks that may re-establish access or run payloads.
- ✗
/var/log/auth.log
Why it's wrong here
The auth.log records authentication events, such as SSH logins and sudo usage. It is useful for identifying the initial compromise and attacker actions, but it is not a persistence location. Persistence mechanisms are files or configurations that ensure the attacker retains access, not logs of past events.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official GIAC exam blueprint
This GCIH practice question is part of Courseiva's free GIAC certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the GCIH exam.