This rule is designed to detect the creation of AWS API access keys for IAM (Identity and Access Management) users, where the key is created by a different IAM user. Such activity can signal an attempt to establish unauthorized, persistent access within the AWS environment, often referred to as a backdoor. The presence of backdoored users poses a significant security threat, allowing malicious actors to access resources with permissions granted to the compromised user accounts. This detection is implemented through AWS CloudTrail logs, specifically monitoring events originating from the IAM service, focusing on the 'CreateAccessKey' action. If an API call matches the designated source and the resulting user identity indicates that the key was not created by the intended user (through the specified filter), an alert is generated. Overall, this rule helps in monitoring AWS key management and identifying potential security breaches stemming from unauthorized key creations.