Why A is the Correct Answer:
A supply chain attack is exactly what the organization is trying to mitigate. By creating a registry of known- good software packages and their hashes, they can verify that the packages they are using are legitimate and haven't been altered.
If an attacker were to compromise a software package in the supply chain, the hash of the altered package would not match the hash in the organization's registry. This would immediately alert the organization to a potential compromise.
CASP+ Relevance: This aligns with the CASP+ exam objectives, which emphasize the importance of risk management, threat intelligence, and implementing security controls to address various attack vectors, including supply chain risks.
How the Registry Works (Elaboration based on CASP+principles):
Hashing: When a package is vetted, a cryptographic hash function (like SHA-256) is used to generate a unique "fingerprint" (the hash) of the package's contents.
Verification: Before installing or using a package, its hash is calculated and compared to the hash stored in the registry. A match confirms the package's integrity. A mismatch indicates tampering.
Incident Response: If a vulnerability is discovered in a commonly used package, the registry helps the organization quickly identify which systems are affected based on the dependency list and the stored hashes.
In conclusion, maintaining a registry of software dependencies with hashes is a crucial security control that directly addresses the threat of supply chain attacks by ensuring the integrity and authenticity of software packages. The use of hash functions for verification is a common practice in security and is emphasized in the CASP+ material.