This CEH practice question tests your understanding of advanced topics: wireless, cloud, iot, cryptography. 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 attacks target cryptographic weaknesses?
Downgrade attack
Forces a system to use weaker, more vulnerable encryption.
Replay attack
Replays captured encrypted messages without breaking encryption but exploits lack of freshness.
Cross-site scripting
Why wrong: XSS is a client-side attack, not cryptographic.
Birthday attack
Exploits collisions in hash functions.
SQL injection
Why wrong: SQL injection is a code injection, not cryptographic.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Downgrade attack
A downgrade attack is correct because it forces a system to use a weaker, less secure cryptographic protocol or algorithm (e.g., forcing TLS 1.2 down to SSL 3.0 or using export-grade ciphers). This exploits the cryptographic weakness of the older protocol, making it easier for an attacker to decrypt or manipulate the communication. The attack directly targets the cryptographic strength of the negotiated security parameters.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Downgrade attack
Why this is correct
Forces a system to use weaker, more vulnerable encryption.
Related concept
Read the scenario before looking for a memorised answer.
Replay attack
Why this is correct
Replays captured encrypted messages without breaking encryption but exploits lack of freshness.
Related concept
Read the scenario before looking for a memorised answer.
Cross-site scripting
Why it's wrong here
XSS is a client-side attack, not cryptographic.
Birthday attack
Why this is correct
Exploits collisions in hash functions.
Related concept
Read the scenario before looking for a memorised answer.
SQL injection
Why it's wrong here
SQL injection is a code injection, not cryptographic.
Common exam traps
The trap here is that candidates often confuse 'replay attack' (option B) as purely a cryptographic attack, but it is actually a protocol-level attack that can succeed even with strong cryptography if no nonce or timestamp is used, while the Birthday attack (option D) is a direct cryptographic weakness based on hash collision probability.
Detailed technical explanation
A downgrade attack often leverages protocol negotiation mechanisms like the TLS handshake's 'ClientHello' and 'ServerHello' messages, where an attacker can strip supported cipher suites or force fallback to a vulnerable version (e.g., POODLE attack on SSL 3.0). In practice, this is mitigated by implementing TLS_FALLBACK_SCSV (Signaling Cipher Suite Value) as defined in RFC 7507, which prevents forced downgrades. The Birthday attack (option D) exploits the mathematical property of hash collisions, where finding two inputs with the same hash becomes feasible when the output space is too small (e.g., 64-bit hash), allowing forgery or authentication bypass.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the CEH 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.
What to study next
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FAQ
Advanced Topics: Wireless, Cloud, IoT, Cryptography — This question tests Advanced Topics: Wireless, Cloud, IoT, Cryptography — Read the scenario before looking for a memorised answer..
The correct answer is: Downgrade attack — A downgrade attack is correct because it forces a system to use a weaker, less secure cryptographic protocol or algorithm (e.g., forcing TLS 1.2 down to SSL 3.0 or using export-grade ciphers). This exploits the cryptographic weakness of the older protocol, making it easier for an attacker to decrypt or manipulate the communication. The attack directly targets the cryptographic strength of the negotiated security parameters.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 2026
This CEH practice question is part of Courseiva's free EC-Council 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 CEH exam.
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