https://github.com/code-423n4/2024-07-karak?tab=readme-ov-file#eip-compliance-checklist states that DSS contract should comply with ERC-165. Therefore, the protocol requires that each DSS is ERC-165 compliant.
According to https://eips.ethereum.org/EIPS/eip-165#how-a-contract-will-publish-the-interfaces-it-implements, A contract that is compliant with ERC-165 shall implement the following interface:
Thus, each DSS needs to implement the ERC165.supportsInterface function to comply with ERC-165. However, calling the following Core.registerDSS function does not check if the DSS implements the ERC165.supportsInterface function or not so a DSS that does not implement the ERC165.supportsInterface function and hence is not ERC-165 compliant can also be registered.
https://github.com/code-423n4/2024-07-karak/blob/53eb78ebda718d752023db4faff4ab1567327db4/src/Core.sol#L262-L267
For a DSS that does not implement the ERC165.supportsInterface function, calling the following callHookIfInterfaceImplemented function returns false without further calling the DSSs corresponding hook even if such DSS does implement such hook. In this situation, although the DSS expects the relevant hooks to be called, all of these hooks fail to be called; for instance, such DSSs registrationHook function cannot be called at all so it fails to only accept its chosen operators even though https://github.com/code-423n4/2024-07-karak?tab=readme-ov-file#dss-distributed-secure-services states that DSS would be able to choose which operator it would like to accept.
https://github.com/code-423n4/2024-07-karak/blob/d19a4de35bcaf31ccec8bccd36e2d26594d05aad/src/entities/HookLib.sol#L78-L103
The Core.registerDSS function can be updated to only allow DSSes that do implement the ERC165.supportsInterface function and comply with ERC-165 to be registered.
