Driven by increased crackdowns on BitTorrent sites such as The Pirate Bay, software pirates are fast-moving their warez to file-hosting Web sites.

Sites such as RapidShare, Megaupload, and Hotfile let anonymous users upload large files such as cracked software for free.

Hyperlinks to the software can then be distributed by pirates via Web sites, instant messages, or social media sites such as Twitter, said Vic DeMarines, vice president of products at anti-piracy software vendor V.I. Labs.

"It's incredibly easy to use. And what you get is essentially your own private FTP server," DeMarines said.

While sites such as RapidShare allow free downloads, they make their money by charging heavy downloaders for premium memberships. These memberships, such as the 30-day premium access for 6.99 euros (about $10 US) at Rapidshare, let users download files immediately and without any caps on bandwidth.

Trade in pirated digital goods, whether it is movies, music or e-books or software, is what drives the popularity and business model of firms like RapidShare. The site told The New York Times earlier this year that it hosted 10 petabytes of data and up to 3 million downloaders at a time.

The Association of American Publishers estimates that half of the pirated books found by its members were linked to Rapidshare.

"There's a lot of money being made," said DeMarines. "Without hosting pirated goods, I'm not sure what their revenue model would be."

According to a recent investigation by V.I. Labs into the availability of pirated software from a sample of 43 vendors, 100% were on RapidShare.

A spokeswoman for Cham, Switzerland-based Rapidshare declined to comment on the V.I. Labs report, saying she would need more information.

The site is already among the top 20 most popular in the world, according to Alexa. Uploads and downloads to Rapidshare account for 5% of all Internet traffic globally, says German networking vendor Ipoque.

Though Rapidshare has faced lawsuits related to piracy, DeMarines said it and other file-hosting sites are tricky to prosecute because uploaders are not required to register or identify themselves. Also, Rapidshare tries to distance itself from any knowledge of the pirated goods by not filtering or monitoring the content on its servers.

"For us, everything is just a file, no matter what," a spokeswoman told The Times in March. DeMarines said Rapidshare does comply with the Safe Harbor Provisions of the U.S.' Digital Millennium Copyright Act (DMCA) by quickly taking down pirated files when notified by the copyright holders.

The company even grants certain organizations direct access into their service, so that they can go ahead and delete the hyperlinks and pirated files themselves, DeMarines said.

Peer-to-peer networking (P2P) does still remain the largest channel for distributing pirated software, movies and other digital content. Ipoque said it enables between 43% to 70% of piracy, depending on the region of the world.

The most popular network remains BitTorrent, which is used by six out of 10 P2P users, V.I. Labs said.

eDonkey is a distant second, with 20% share, despite hosting almost 900,000 users and 77 million files at any given time. Once-popular Gnutella is ranked third, with a market-share in the single digits.

But file hosting is growing much faster, Ipoque said, already enabling between 15% to 35% of digital piracy, depending on the region of the world.

DeMarines said he expects file-hosting sites to eventually supplant P2P. "P2P is on its way down. They're too visible, and so the copyright organizations are going to take these BitTorrent tracker sites out," he said.

Other long-running methods for distributing warez are either stagnant or shrinking. Usenet newsgroups, for instance, have lost popularity due to the large amount of pornography and malware mingled in with the warez, DeMarines said.

Internet Relay Chat (IRC) is "not favored" as a way to transmit files, though announcements and links on IRC to warez hosted on file-hosting sites is growing, DeMarines said.