"Angry Birds: Space," the latest installment of the insanely popular mobile game, is being used to mask some fairly nasty malware, according to security experts and Rovio, the maker of "Angry Birds."

Graham Cluley, an analyst with Web security firm Sophos, wrote on the company's blog Thursday that they had discovered fake versions of the game on unofficial app stores. The fake games contain a "Trojan horse" virus.

A post on Rovio's blog on Thursday also warned fans to watch out for fake versions of the game, urging them to download the new title from their official store.

According to Sophos, the Trojan horse, which it identified in a file called Andr/KongFu-L, appears to be a fully functional version of the game, but instead installs a virus on the user's smartphone or tablet.

From there, the code tries to install more malware that essentially puts the phone or tablet computer under the control of the cybercriminals behind it, Cluley wrote.

"It feels like we have to keep reminding Android users to be on their guard against malware risks, and to be very careful, especially when downloading applications from unofficial Android markets," he said.

Unlike Apple, which screens all its apps and requires iPhone and iPad owners to download software from its official App Store, Google maintains less control over what people can install on devices that run its Android operating system. The company allows Android owners to download programs from official and unofficial sources.

Security experts say Android device owners should use the official Android Market if they want to avoid downloading fake apps and potentially harmful programs, although there have been instances of malicious software showing up in that official venue, too.

From Harry Potter to Ana Kournikova, it's not unusual for malicious hackers to use popular topics, often from the entertainment and celebrity world, to lure potential victims.

"Angry Birds: Space" was released March 22 for the iPhone, iPad and Android devices, as well as Macs and PCs. It soared to a mind-blowing 10 million downloads in just three days, three times faster than the franchise's last outing, "Angry Birds: Rio."

Released in 2009, "Angry Birds" is the No.1 paid mobile app of all time, crossing 300 million downloads, across multiple platforms, last year.

Based in Finland, Rovio parlayed the game's success into a virtual empire, offering everything from comic books and animated videos to plush dolls and cookbooks based on the game.