This rule detects the assumption of roles within AWS Security Token Service (STS) by users or roles, which can be employed for legitimate administrative purposes or malicious intent. The rule specifically targets `AssumeRole` actions in AWS CloudTrail logs that indicate successful role assumptions by either IAM users or assumed roles. The detection hinges on identifying specific fields within CloudTrail logs to verify user identity, session details, and the roles being assumed. Adversaries may leverage this action to gain temporary access to AWS resources for privilege escalation or lateral movement. Investigations may require scrutinizing user actions leading to the assumption, validating the legitimacy of the role, and correlating with other relevant events to assess potential misuse.