Lust seems to be prevailing over caution for computer users in China who download certain unauthorized copies of Ang Lee's latest film: some of them are receiving dozens of viruses instead.

Because "Lust, Caution" was released in China with about 30 minutes of footage censored by the local film overseer -- almost all of it depicting graphic sex -- movie audiences here are turning to unauthorized downloads of the film to see what they missed.

However, hackers are replacing what appear to be copies of the film with software that infects end users' computers, according to a warning from antivirus software maker Beijing Rising International Software..

Rising's antivirus software first flagged the problem on Friday or Saturday, said spokeswoman Li Ting. Rising estimates that about 15 percent of the copies of "Lust, Caution" available online would supply frustration rather than titillation, causing a blue screen to appear on the user's computer and possibly stealing passwords for Web sites and instant messaging programs.

Rising has designated the "Lust" virus as Trojan.Win32.Mnless.zgw. This type of attack is on the rise against users downloading entertainment content, including movies, music, and photos of film and pop stars, the company said. Rising offers a fix via its Chinese Web site.

Some users are downloading "dozens" of viruses, according to Gao Yiwei, a product manager with Kaspersky Lab in China. Not all users are getting the same thing: some receive only Trojan horse software, while others receive both the film and various viruses. Kaspersky's software now protects against the viruses, Gao said, but he wouldn't confirm when they first appeared or when the software update occurred.

A representative for another antivirus software company, Trend Micro, said she would pass the information on to technical support and would "fix this problem soon in China."

Unauthorized downloading of films is common in China, part of a large piracy problem that affects both the entertainment and software industries. Organizations like the Business Software Alliance (BSA) regularly point out that pirated software can contain viruses or be more vulnerable to attacks. The Motion Picture Association -- Hollywood's overseas lobbying body -- estimates that illegal reproduction and unauthorized downloads of films caused the film industry to miss out on US$2.7 billion in potential revenue in China in 2005.