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Difficulty: MediumCryptographic and Security Control Weaknesses

An enterprise software vendor distributes signed firmware updates to industrial IoT controllers. A recent security audit reveals that while the vendor uses a 2048-bit RSA key for asymmetric signing, the update process relies on the SHA-1 hashing algorithm to compute message digests. Which of the following best describes the primary security risk created by using SHA-1 for digital signature generation?

  1. An adversary could forge a malicious firmware image that yields an identical digest, bypassing signature verification controls.Answer
  2. B
    An eavesdropper on the network can easily decrypt the underlying firmware binary because SHA-1 operates as a symmetric bulk encryption algorithm.
  3. C
    Target IoT controllers will fail to validate signatures because SHA-1 digests cannot be processed during the Certificate Signing Request lifecycle.
  4. D
    Network firewalls will misclassify the signed software payload as active malware and block incoming transmission streams.

Answer

An adversary could forge a malicious firmware image that yields an identical digest, bypassing signature verification controls.
The correct answer highlights the risk of cryptographic hash collisions. SHA-1 is computationally susceptible to collision attacks, meaning an attacker can craft a altered file that produces the exact same hash output as a legitimate file. When signed by the vendor's private key, the system accepts the malicious software as authentic.

Step-by-Step Solution

1
Analyze the cryptographic weak point identified in the scenario.
The scenario highlights the reliance on SHA-1 for message digest generation prior to RSA signing.
While RSA-2048 provides strong key strength, digital signatures rely on the cryptographic resistance of the hashing algorithm.
2
Evaluate the primary vulnerability associated with deprecated hash algorithms like SHA-1.
SHA-1 lacks sufficient collision resistance.
Cryptographic collisions allow two different datasets (such as a valid firmware update and a trojanized binary) to output the same hash value.
3
Determine the impact of a hash collision on digital signature verification.
The recipient's verification process computes the hash of the malicious file, finds it matches the signature, and trusts the forged payload.
This compromises code integrity and authenticity, allowing unauthenticated code execution.

Key Concept

Cryptographic Hash Collision Vulnerabilities
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Topics

Cryptographic and Security Control Weaknesses

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