This detection rule identifies the installation of the Atera Remote Monitoring & Management (RMM) agent on Windows systems, particularly focusing on the EventID 1033 emitted by the MsiInstaller service. The rule is significant because the Atera agent has been associated with Conti ransomware operations, thereby presenting a notable threat vector. The detection is primarily condition-based on the presence of the 'AteraAgent' string in the messages generated during the installation process. While the rule aims to catch malicious installations, it is essential to consider that legitimate installations of the Atera agent may trigger false positives. As such, this rule is classified at a high severity level due to the potential risks associated with unauthorized or malicious use of the software.