This detection rule is designed to identify unauthorized changes to the user account associated with the FAX service in Windows environments. By monitoring registry modifications, the rule specifically focuses on the `TargetObject` path `HKLM\System\CurrentControlSet\Services\Fax\ObjectName`. The key goal is to prevent privilege escalation that may occur if the FAX service’s user account is altered maliciously. The rule is set at a high severity level and is triggered by changes that meet the selection criteria but do not match the filter, specifically filtering out legitimate changes that revert the account to `NetworkService`. The importance of this rule stems from the FAX service often being a target for lateral movement within a network, making robust detection crucial for maintaining security integrity.