The correct answer is to implement per-record encryption keys derived from a master key combined with a unique salt. This remediation directly addresses the core vulnerability exposed in the breach: using a single, static key for all records allows an attacker who compromises that key to decrypt the entire database at once. By deriving a unique encryption key for each record from a master key and a record-specific salt, the per-record encryption key derivation ensures that even if the master key is later compromised, the attacker must perform a separate, computationally expensive derivation for every single stolen record, making bulk decryption infeasible. On the Certified Ethical Hacker CEH exam, this scenario tests your understanding of cryptographic key management failures, specifically the difference between key reuse and key diversification. A common trap is to suggest rotating the master key or changing the IV, but those do not prevent decryption of already-exfiltrated data if the same key was used for all records. Memory tip: think “one salt per record, one key per breach” — without the unique salt, the master key is a skeleton key to the whole database.
CEH Cryptography and Malware Analysis Practice Question
This CEH practice question tests your understanding of cryptography and malware analysis. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
You are a security analyst for a medium-sized company. The company uses a custom web application for internal project management. The application uses AES-256-CBC for encrypting sensitive data stored in the database. Recently, the company experienced a data breach where an attacker exfiltrated the entire database. Although the data was encrypted, the attacker was able to decrypt some records. Investigation reveals that the encryption key is stored in a configuration file on the same server, and the initialization vector (IV) is hardcoded in the application code. Additionally, the application uses the same key for all records. Which of the following is the most effective remediation to prevent future decryption of stolen encrypted data?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Implement per-record encryption keys derived from a master key combined with a unique salt
Option D is correct because using per-record encryption keys derived from a master key combined with a unique salt ensures that even if an attacker exfiltrates the entire database, each encrypted record requires a separate key derivation operation. Without the unique salt per record, the attacker cannot decrypt all records even if they compromise the master key. This approach mitigates the risk of a single key compromise leading to bulk decryption, which is the core vulnerability in the current setup where the same AES-256-CBC key and hardcoded IV are reused across all records.
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.
✗
Change the encryption mode from CBC to GCM to provide authentication
Why it's wrong here
GCM provides integrity but does not solve the key reuse issue.
✗
Store the encryption key in a hardware security module (HSM) and use the same key
Why it's wrong here
While HSM improves key storage, using the same key for all records still allows decryption of all if the key is extracted.
✗
Rotate the encryption key every 24 hours
Why it's wrong here
Key rotation does not protect records encrypted with old keys if those keys are compromised.
✓
Implement per-record encryption keys derived from a master key combined with a unique salt
Why this is correct
Each record gets a unique key; compromise of one key does not affect others.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often focus on key storage or rotation (options B and C) as the primary solution, overlooking that the real vulnerability is the reuse of a single key across all records, which allows an attacker to decrypt the entire dataset with a single key compromise.
Detailed technical explanation
How to think about this question
In AES-256-CBC, the same key and IV produce identical ciphertext for identical plaintext blocks, making the encryption deterministic and vulnerable to pattern analysis. Deriving per-record keys using a key derivation function (KDF) like PBKDF2 or HKDF with a unique salt per record ensures that each record is encrypted with a distinct key, so compromising the master key requires the attacker to brute-force each salt-key derivation individually. In practice, this is often implemented as envelope encryption, where a master key encrypts a per-record data key, and the encrypted data key is stored alongside the ciphertext, preventing bulk decryption even if the master key is exposed.
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 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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CEH question in full detail.
Cryptography and Malware Analysis — This question tests Cryptography and Malware Analysis — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Implement per-record encryption keys derived from a master key combined with a unique salt — Option D is correct because using per-record encryption keys derived from a master key combined with a unique salt ensures that even if an attacker exfiltrates the entire database, each encrypted record requires a separate key derivation operation. Without the unique salt per record, the attacker cannot decrypt all records even if they compromise the master key. This approach mitigates the risk of a single key compromise leading to bulk decryption, which is the core vulnerability in the current setup where the same AES-256-CBC key and hardcoded IV are reused across all records.
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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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