Researchers have discovered another feature of the Conficker worm that provides an additional clue about the intent of the creators–the worm installs malware that masquerades as antivirus software, Trend Micro said on Friday.

The worm, which has infected millions of Windows-based computers on the Internet, is downloading a program called Spyware Protect 2009 and displaying warning messages saying that the computer is infected and offering to clean it up for $49.95, according to the Trend Micro blog.

The infection alerts repeatedly appear and experts are worried that people may be clicking on them and paying for the software just to be rid of the annoying messages, thereby handing thieves their credit card information.

The fake antivirus program also attempts to install a Trojan downloader that is programmed to download new versions of Spyware Protect 2009, according to Kasperky Lab’s blog. However, the domain the Trojan downloader was being accessed from has been shut down, the blog said.

The fake antivirus feature further bolsters the speculation that the motivation behind the worm is to make money and not a desire to disrupt computer or network operations.

Researchers were still analyzing new component code of the worm that began being spread via peer-to-peer and being downloaded off domains that host the Waledec worm on Wednesday but were finding the task difficult because the instructions are encrypted.

The worm spreads via a hole in Windows that Microsoft patched in October, as well as through removable storage devices and network shares with weak passwords. The worm disables security software and blocks access to security Web sites.