Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
A security analyst is reviewing the source code of a custom authentication service. The service uses a function that compares a user-supplied password to the stored password hash by iterating through each byte and returning false immediately upon the first mismatch. The analyst measures the function's execution time and discovers it varies measurably depending on how many initial bytes match. Which type of attack is this vulnerability most likely to facilitate?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Distractor review
Brute-force attack
A brute-force attack attempts every possible combination of characters, which is computationally expensive and does not leverage timing variations. While an attacker could eventually guess the password, the timing vulnerability specifically enables a more efficient attack.
B
Distractor review
Dictionary attack
A dictionary attack uses a precomputed list of common passwords or phrases, and does not utilize execution time measurements. It relies on the likelihood that users choose weak passwords, not on side-channel information like timing.
C
Distractor review
Replay attack
A replay attack involves intercepting a valid authentication token (such as a session cookie or hashed password) and retransmitting it to impersonate the user. It does not involve manipulating or measuring execution time of a comparison function.
D
Best answer
Timing attack
A timing attack exploits measurable variations in the time it takes to execute a cryptographic operation. In this case, the early-exit comparison enables an attacker to deduce the correct secret byte by byte, making it the correct classification.
Common exam trap
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.
Technical deep dive
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.
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More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A laptop is suspected of being used in a malware incident. It is still powered on and connected to Wi-Fi. What should the responder do before shutting it down?
Question 2
An employee reports a ransomware note on a file server. The server is still powered on, shares are still being accessed, and management wants service restored as quickly as possible. What should the incident response team do first?
Question 3
An employee reports a ransomware note on a finance laptop. The laptop is still powered on, connected to Wi-Fi, and the user says they were just working in a spreadsheet. Management wants the fastest safe response that also preserves evidence. What should the responder do first?
Question 4
You are handed a company laptop suspected in an insider theft case. Legal says the evidence may be needed in court. Which action best preserves admissibility?
Question 5
A developer wants to reduce the risk of SQL injection in a new customer search form. Which two changes are the best mitigations? Select two.
Question 6
A branch office uses a flat LAN, and a compromise on one user workstation could spread quickly to finance systems. Management wants finance workstations isolated from general users, but finance staff still need access to a central finance application and network printer. What is the best design change?
FAQ
Questions learners often ask
What does this SY0-701 question test?
Read the scenario before looking for a memorised answer.
What is the correct answer to this question?
The correct answer is: Timing attack — The described vulnerability is a timing side-channel. When a comparison function returns early upon the first mismatch, an attacker can send many carefully crafted guesses and measure the response time. A slightly longer execution time indicates that more initial bytes matched. By iterating through all possible byte values, the attacker can recover the entire secret (password or hash), byte by byte. This is a well-known attack against non-constant-time cryptographic comparisons. Mitigations include using constant-time comparison functions.
What should I do if I get this SY0-701 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
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