File transfer protocol (FTP) is a service that allows users to transfer files between computers over a network.
If enabled within firewall rules, FTP would present the greatest risk, as it can expose sensitive data to unauthorized access, modification, or deletion. FTP does not provide encryption or authentication, which makes it vulnerable to eavesdropping, spoofing, and tampering attacks. Simple mail transfer protocol (SMTP), simple object access protocol (SOAP), and hypertext transfer protocol (HTTP) are also services that can be used to exchange data over a network, but they have more security features than FTP, such as encryption, authentication, or validation. References: CISA Review Manual (Digital Version)

The best way to mitigate the risk associated with unintentional modifications of complex calculations in end-user computing (EUC) is to execute copies of EUC programs out of a secure library. This will ensure that the original EUC programs are protected from unauthorized changes and that the copies are run in a controlled environment. A secure library is a repository of EUC programs that have been tested, validated, and approved by the appropriate authority. Executing copies of EUC programs out of a secure library can also help with version control, backup, and recovery of EUC programs. Having an independent party review the source calculations, implementing complex password controls, and verifying EUC results through manual calculations are not as effective as executing copies of EUC programs out of a secure library, as they do not prevent or detect unintentional modifications of complex calculations in EUC. References: End-User Computing (EUC) Risks: A Comprehensive Guide, End User Computing (EUC) Risk Management

The IS auditor should review the processes for making changes to cloud environment specifications, as these are the inputs for the predefined automated procedures that deploy and configure the application infrastructure. The IS auditor should verify that the changes are authorized, documented, tested, and approved before they are applied to the cloud environment. The IS auditor should also check that the changes are aligned with the business requirements and do not introduce any security or performance issues.
References
ISACA CISA Review Manual, 27th Edition, page 254
Configuration Management in Cloud Computing - ScienceDirect
Cloud Configuration Management - BMC Software