What STRIDE category applies to a transaction identification issue caused by a shared symmetric key among multiple servers?

The scenario described involves a transaction identification issue that arises from the use of a shared symmetric key among multiple servers. In the context of the STRIDE threat modeling framework, the category that best fits this scenario is repudiation.

Repudiation refers to the ability of an entity to deny having performed an action or a transaction. In scenarios where multiple servers share a symmetric key, it becomes challenging to uniquely identify which server initiated a particular transaction. Consequently, if a transaction occurs, and one of the servers is compromised or if the transaction is called into question, the server can deny responsibility. This can lead to a lack of accountability, as the parties involved may not be able to definitively prove who performed a specific action.

When using shared keys, there is also the risk of ambiguity in transaction attribution, which further enables repudiation. Since the same key is used by different servers, any transactions made with that key lack distinct identifiers that could be used to trace back to the individual servers.

In contrast, the other categories such as impersonation, information disclosure, and denial of service do not directly address the issue of transaction identification tied to the shared symmetric key. Impersonation involves someone pretending to be another entity, information disclosure relates to unauthorized access to data