In some cases, the victims' own boyfriends or relatives were responsible for the crimes, in a troubling reflection of South Korea's deep-rooted patriarchal norms.
The number of spycam crimes reported to police has surged from around 1,100 in 2010 to more than 6,500 last year.
Tens of thousands of South Korean women on Saturday protested against secretly-filmed spycam pornography as anger over the issue swells, prompting national soul-searching.
But these advances have also given rise to an army of tech-savvy peeping Toms, with videos widely shared in internet chatrooms and on file-sharing sites, or used as adverts for websites promoting prostitution.
Asia's fourth-largest economy takes pride in its tech prowess, from ultra-fast Internet to cutting-edge smartphones.