Zone-H.org, a Web site that records defacements, reported that the hacker broke into the Paramount Pictures-owned Web site on Sunday. The content, including a trailer for the movie featuring Tom Cruise, was replaced by black-and-white graphics and a message from the hacker.
The defacer, who goes by the nickname "Un-root," apparently hacked the Linux system through a vulnerability in an Apache Web server.
"That is embarrassing for them," said Jason Hart, director of security for WhiteHat UK. "If you look at Zone-H, there are a lot of hackers coming out of Brazil. It may be the increase in broadband or wireless access points. But there are certainly more."
Hart added that poorly patched servers were often the cause of many defacements.
"People are becoming more relaxed about security," Hart said. "It's about basic steps--just keep testing and have simple security frameworks. People think you need sophisticated answers, but you don't. Just make sure you have patch management."
The site for "War of the Worlds," the film version of H.G. Wells' novel, had been restored by Monday lunchtime in the United Kingdom. Paramount Pictures was unable to comment on the incident at the time of writing.
Last year, Brazilian federal police arrested 53 suspects on charges of stealing $93 million from online banking customers. Security experts have said that Brazil is a hacking hot spot of the world.
Dan Ilett of ZDNet UK reported from London.