diff --git a/agent/session/shell/shell_unix.go b/agent/session/shell/shell_unix.go
index b1ca3590c..3daa1f19e 100644
--- a/agent/session/shell/shell_unix.go
+++ b/agent/session/shell/shell_unix.go
@@ -116,6 +116,12 @@ func StartCommandExecutor(
 			if strings.TrimSpace(config.RunAsUser) == "" {
 				return errors.New("please set the RunAs default user")
 			}
+			
+			if strings.TrimSpace(config.RunAsUser) == "ssm-user" {
+				// Start as ssm-user
+				// Create ssm-user before starting a session.
+				u.CreateLocalAdminUser(log)
+			}
 
 			// Check if user exists
 			if userExists, _ := u.DoesUserExist(config.RunAsUser); !userExists {