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SSCP Practice Question: A security team discovers that a legacy system…
A security team discovers that a legacy system uses ECB mode to encrypt credit card numbers. What is the primary security concern with this mode?
⚠ Common exam trap
Test-takers frequently confuse ECB's lack of diffusion with performance issues or integrity flaws, but The SSCP exam specifically tests whether you recognize that ECB's deterministic block mapping is its fundamental weakness, not speed or padding vulnerabilities.
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
✓
Identical plaintext blocks produce identical ciphertext, revealing patterns
ECB (Electronic Codebook) mode encrypts each plaintext block independently using the same key. This means identical plaintext blocks produce identical ciphertext blocks, which allows an attacker to detect patterns, data boundaries, and repetitions in the encrypted data. For credit card numbers, which often have predictable formats (e.g., BIN ranges, fixed lengths), this pattern leakage can reveal sensitive information without breaking the encryption key.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Identical plaintext blocks produce identical ciphertext, revealing patterns
Why this is correct
This is the classic weakness of ECB.
- ✗
It is slow compared to other modes
Why it's wrong here
ECB is actually fast because it's parallelizable.
- ✗
It is vulnerable to padding oracle attacks
Why it's wrong here
Padding oracle attacks target CBC, not ECB.
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It does not provide integrity
Why it's wrong here
No mode without MAC provides integrity, but that's not the main issue.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This SSCP practice question is part of Courseiva's free ISC2 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 SSCP exam.