Session Manager is an AWS Systems Manager feature that lets administrators open controlled remote sessions to managed instances without exposing inbound SSH or RDP ports. It can also support port forwarding, allowing a client to reach a service on the target instance through an authenticated management tunnel. Because access is brokered through AWS identities and Systems Manager permissions, it is a common choice for secure administration in cloud environments.
In security terms, Session Manager is important because the session itself becomes part of the trust boundary. If permissions are too broad, or if destination checks in port forwarding are weak, an authorized user may be able to reach services that were meant to stay local, such as instance metadata endpoints. That can expose temporary IAM credentials and turn a convenience feature into a credential-risk path. Defenders should tightly scope who can start sessions, restrict which documents can be used, and monitor remote-host forwarding carefully.