The DSP-W215 contains an unauthenticated stack overflow that can be exploited to take complete control of the device, and anything connected to its AC outlet.
This is actually one of the many problems with HNAP.

You can read more about this here.
http://www.devttys0.com/2014/05/hacking-the-d-link-dsp-w215-smart-plug/

BR,
[ Gunther ]