Researchers say the behavior amounts to a persistent backdoor.
rom the department of head scratches comes this counterintuitive news: Microsoft says it has no plans to change a remote login protocol in Windows that allows people to log in to machines using passwords that have been revoked.

Password changes are among the first steps people should take in the event that a password has been leaked or an account has been compromised. People expect that once they've taken this step, none of the devices that relied on the password can be accessed.

The Remote Desktop Protocol—the proprietary mechanism built into Windows for allowing a remote user to log in to and control a machine as if they were directly in front of it—however, will in many cases continue trusting a password even after a user has changed it. Microsoft says the behavior is a design decision to ensure users never get locked out.

Independent security researcher Daniel Wade reported the behavior earlier this month to the Microsoft Security Response Center. In the report, he provided step-by-step instructions for reproducing the behavior. He went on to warn that the design defies nearly universal expectations that once a password has been changed, it can no longer give access to any devices or accounts associated with it.