This detection rule identifies potentially malicious usage of the AWS STS (Security Token Service) AssumeRole API, which allows one AWS identity to assume the permissions of another role temporarily. The misuse of AssumeRole is often a sign that an attacker is attempting to move laterally or escalate privileges within an AWS environment. The rule specifically targets user identities of type 'AssumedRole' where the session issuer also matches a type of 'Role', as such patterns may indicate unauthorized access attempts. Given the nature of AWS environments, having proper monitoring for role assumption activities is critical for security, as legitimate roles can also be misused if an attacker gains the necessary access privileges. The detection leverages AWS CloudTrail logs, which capture API calls and track changes to resources, ensuring that any suspicious or unauthorized AssumeRole activities can be flagged for further investigation. This rule emphasizes the importance of monitoring account behavior, maintaining a rigid identity and access management policy, and auditing role assignments regularly to minimize the risk of privilege escalation through AssumeRole misuse.