The answer is privilege escalation, with the most likely objective being to gain root access. This is correct because the SUID (Set Owner User ID) bit on a binary owned by root, such as /usr/bin/evil, allows any user who executes it to run the program with root-level permissions, effectively bypassing standard access controls. On the Certified Ethical Hacker CEH exam, this scenario tests your understanding of Linux privilege escalation techniques, often appearing in questions about post-exploitation or backdoor detection. A common trap is confusing SUID with SGID or assuming the binary itself is malicious rather than its permission misconfiguration. Remember the key indicator: a non-standard SUID binary owned by root is almost always a planted backdoor for privilege escalation. Memory tip: "SUID = Switch User ID" — if it’s owned by root and not standard, think "root access for anyone."
CEH Enumeration and System Hacking Practice Question
This CEH practice question tests your understanding of enumeration and system hacking. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 analyst observes a suspicious SUID binary /usr/bin/evil in a Linux system. Which type of vulnerability does this indicate, and what is the MOST likely objective of an attacker who placed it?
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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Privilege escalation; gain root access
A SUID binary owned by root that is not part of the standard OS distribution (like /usr/bin/evil) is a classic indicator of a privilege escalation backdoor. The SUID bit allows any user who executes the binary to run it with the owner's permissions—in this case, root—so the attacker's objective is to gain root access by executing this binary.
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.
✗
Information disclosure; read sensitive files
Why it's wrong here
While a SUID binary could be used to read files, the primary objective is privilege escalation.
✓
Privilege escalation; gain root access
Why this is correct
SUID binaries allow execution with elevated permissions; a root-owned SUID binary can be used to escalate to root.
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.
✗
Denial of service; crash the system
Why it's wrong here
SUID binaries are not typically used for denial of service; they are used for privilege escalation.
✗
Buffer overflow; execute arbitrary code
Why it's wrong here
A buffer overflow is a different type of vulnerability; SUID abuse is about privilege escalation through setuid bits.
Common exam traps
Common exam trap: answer the scenario, not the keyword
EC-Council often tests the distinction between a vulnerability (like a buffer overflow) and an indicator of a completed exploit (like a SUID binary), causing candidates to confuse the attack vector with the attacker's objective.
Detailed technical explanation
How to think about this question
The SUID (Set User ID) permission bit (chmod u+s) causes the process to run with the effective UID of the file owner, not the executing user. Attackers often compile a simple C program (e.g., system("/bin/sh")) and set its SUID bit to root, creating a persistent backdoor. In real-world scenarios, this is commonly found after an attacker gains initial foothold and then escalates to root, leaving the binary for later re-entry.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CEH question in full detail.
Enumeration and System Hacking — This question tests Enumeration and System Hacking — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Privilege escalation; gain root access — A SUID binary owned by root that is not part of the standard OS distribution (like /usr/bin/evil) is a classic indicator of a privilege escalation backdoor. The SUID bit allows any user who executes the binary to run it with the owner's permissions—in this case, root—so the attacker's objective is to gain root access by executing this binary.
What should I do if I get this CEH 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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