AWS SDK for .NET Documentation
MasterUserPassword Property
AmazonAmazon.RDS.ModelModifyDBInstanceRequestMasterUserPassword Did this page help you?   Yes   No    Tell us about it...
The new password for the DB instance master user. Can be any printable ASCII character except "/", """, or "@". Changing this parameter does not result in an outage and the change is asynchronously applied as soon as possible. Between the time of the request and the completion of the request, the MasterUserPassword element exists in the PendingModifiedValues element of the operation response. Default: Uses existing setting Constraints: Must be 8 to 41 alphanumeric characters (MySQL), 8 to 30 alphanumeric characters (Oracle), or 8 to 128 alphanumeric characters (SQL Server).
Note:
Amazon RDS API actions never return the password, so this action provides a way to regain access to a master instance user if the password is lost.
Declaration Syntax
C#
public string MasterUserPassword { get; set; }

Assembly: AWSSDK (Module: AWSSDK) Version: 1.5.60.0 (1.5.60.0)