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Difficulty: HardCryptographic and Security Control Weaknesses

A security analyst reviewing network traffic logs from a global logistics platform notices that high-frequency automated telemetry updates are transmitted using AES encryption. Despite the encryption, an eavesdropper sitting on the network path can easily identify recurring fleet coordinates and status codes because identical 16-byte plaintext blocks consistently produce identical 16-byte ciphertext blocks throughout the session. Which cryptographic weakness is directly responsible for allowing the adversary to reconstruct payload patterns from the intercepted traffic?

  1. Utilization of Electronic Codebook (ECB) mode, which lacks initialization vector randomizationAnswer
  2. B
    Implementation of an asymmetric cipher for bulk data transmission instead of a symmetric stream cipher
  3. C
    Failure to apply transport-layer boundary filtering rules on internal network firewalls
  4. D
    Over-reliance on internal perimeter microsegmentation without enforcing mutual TLS certificate authentication

Answer

The vulnerability is caused by the utilization of Electronic Codebook (ECB) mode, which lacks initialization vector randomization and fails to obscure structural patterns in identical plaintext blocks.
Electronic Codebook (ECB) mode is a deterministic block cipher mode of operation that encrypts every matching plaintext block into the exact same ciphertext block when using the same key. Because ECB does not employ an Initialization Vector (IV) or chain ciphertext across blocks, repetitive structured data (such as fixed-format telemetry or coordinates) remains visually or statistically recognizable in the encrypted stream.

Step-by-Step Solution

1
Analyze the observed security flaw in the scenario
Identical 16-byte plaintext blocks produce identical 16-byte ciphertext blocks across encrypted transmissions.
This pattern leakage indicates a lack of diffusion and pseudo-random initialization across block encryptions.
2
Evaluate block cipher operating modes against the observed behavior
Electronic Codebook (ECB) mode evaluates each plaintext block independently using only the key without an Initialization Vector (IV).
Modes like Cipher Block Chaining (CBC) or Galois/Counter Mode (GCM) utilize IVs to ensure identical plaintexts yield distinct ciphertexts.
3
Select the cryptographic configuration error causing the deterministic pattern output
The system was misconfigured to use AES in ECB mode.
ECB mode deterministically maps input blocks to output blocks, exposing structural data patterns to passive eavesdroppers.

Key Concept

Block Cipher Modes of Operation and Pattern Leakage (ECB Flaw)
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Topics

Cryptographic and Security Control Weaknesses

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