Which type of hash is recommended for addition to custom IOCs to avoid issues?

The recommendation to use SHA-256 for adding custom Indicators of Compromise (IOCs) is based on its robust security features compared to other hash types. SHA-256, part of the SHA-2 (Secure Hash Algorithm 2) family, provides a higher level of collision resistance, making it significantly less susceptible to hash collisions where two different inputs produce the same hash value. This quality is crucial for ensuring the integrity and uniqueness of IOCs in security environments.

In contrast, while MD5 and SHA-1 are also widely recognized hashing algorithms, they have known vulnerabilities. MD5 is particularly prone to collision attacks, which can allow malicious actors to create different data that yields the same MD5 hash. SHA-1, although more secure than MD5, has also been rendered less trustworthy due to recent advancements in computational power and cryptographic analysis that have exposed its weaknesses.

Using any hash indiscriminately can lead to security risks, particularly with older algorithms like MD5 and SHA-1. Therefore, opting for SHA-256 ensures a more secure and reliable method for creating and verifying the integrity of custom IOCs in modern security practices.