The cross-platform virus is relatively simple and appears to have a low impact, according to Kaspersky. Even so, it could be a sign that virus writers are beginning to research ways of writing new code capable of infecting multiple platforms, said Shane Coursen, senior technical consultant at Kaspersky.

In a note on its Web site, the SANS Internet Storm Center (ISC) in Bethesda, Md. said the new virus "is a sign the cross-platform aspects are becoming important. As the developers of viruses continue to research this, we will see more cross-platform malware come about in the future."

The new virus, which Kaspersky calls Virus.Linux.Bi.a/Virus.Win32.Bi.a, is written in assembler and only infects files in the current directory. "However, it is interesting in that it is capable of infecting the different file formats used by Linux and Windows," Kaspersky said.

"It isn't surprising that we are seeing a multi-platform virus," given the growing popularity of Linux on enterprise desktops, Coursen said. "This is simply proof-of-concept code to show this kind of thing can be done."

The new virus shows that malicious hackers may be exploring ways of getting new systems into bot networks, according to Johannes Ullrich, chief technology officer at the SANS ISC. But crafting such multi-platform malware is not particularly easy, he said.