Microsoft Defender AV must block Office communication application from creating child processes.
This policy setting prevents Outlook from creating child processes while still allowing legitimate Outlook functions. This rule protects against social engineering attacks and prevents exploiting code from abusing vulnerabilities in Outlook. It also protects against Outlook rules and forms exploits that attackers can use when a user's credentials are compromised.
How this relates to the STIG checklist: STIG vs SCAP benchmark.