What would be the next step after discovering a breach indicating credential replay?

After discovering a breach indicating credential replay, notifying users to change their passwords is a critical response. This action directly addresses the potential compromise of user accounts. Since credential replay entails that another party has gained access to valid credentials, alerting users to change their passwords helps to minimize the risk of unauthorized access and further exploitation of those accounts.

By updating their passwords, users can effectively secure their accounts, particularly if the compromised credentials are still active. This step is often essential in encouraging good security hygiene and can be part of a broader incident response strategy. However, simply notifying users is not the only action necessary; it should be part of a comprehensive plan that might also include implementing other security measures, such as two-factor authentication, to prevent similar breaches in the future.

In this scenario, while other options might also contribute to strengthening security, they do not directly address the immediate need to secure potentially compromised user accounts as effectively as prompting users to change their passwords.