The detection rule `AWS.IAMUser.ReconAccessDenied` focuses on identifying reconnaissance activities performed by IAM users who consistently generate 'access denied' API calls within the AWS environment. Such behavior may indicate an attempt to gather information about resources or permissions that the user does not have access to, which can be a precursor to malicious activity or unauthorized access attempts. The rule triggers when the volume of denied requests by a single IAM user exceeds a defined threshold within a specified time period. Other attributes recorded include event names, user agents, IP addresses, and error messages, which can help in further investigation of suspicious user behavior. The severity level of the rule is set to 'Info', prompting investigation when the threshold is met, thereby allowing security teams to analyze potential reconnaissance efforts without immediately escalating it to higher alert levels.