SAN FRANCISCO (AFP) - While stunning televisions and sizzling content services starred at the Consumer Electronics Show, not far away a light was shined on cable service plundering pirates.

"Pirates closely follow legitimate technology innovations," Irdeto senior security director Mark Mulready told AFP while demonstrating streaming television piracy gear and tactics in hotel suite not far from the CES show floor that closed on Friday.

"Pirates are moving to re-broadcast over set-top boxes."

And piracy has become such an established and lucrative business that it can be challenging for consumers to figure out which streaming television services are legitimate, according to Mr Mulready.

Irdeto, an arm of South Africa-based Internet services titan Naspers, specialises in hunting down and sinking pirates.

"Set-top box piracy is really a global problem that is growing very fast," Mr Mulready said.

Manufacturers in China openly hawk set-top boxes that pirates can distribute to subscribers, according to Irdeto.

The set-top boxes themselves are legal, the trouble begins when pirates rampantly restream cable programmes without permission.

"They basically take what's coming through a legitimate set-top box and re-stream it," Mr Mulready said. "Unfortunately, it is terribly easy."

The top show on pirated boxes last year was Game Of Thrones, followed by The Walking Dead and Breaking Bad, according to Irdeto data.

An aspiring pirate can buy 500 boxes for less than US$21,000 (S$28,000) and bring in US$173,000 in annual subscription revenue from customers who pay an average of US$390 for 12 months of access, according to Irdeto, which buys boxes undercover in its investigations.

In 2013, Google searches for set-top boxes allowing access to pirated content surpassed online hunts for legitimate boxes, Mr Mulready said.