A Russian security company announced Friday that it had found a cross-over virus that can infect PCs running either the open-source Linux or Microsoft Windows operating systems.

Dubbed "Linux.Bi.a" and "Win32.Bi.a," the split-personality malware doesn't do any damage. Instead, said Moscow-based Kaspersky Labs in an online briefing, it's a proof-of-concept to prove that a cross-platform virus is possible.

"However, our experience shows that once proof-of-concept code is released, virus writers are usually quick to take the code, and adapt it for their own use," wrote a Kaspersky analyst in the briefing.

The SANS Institute's Internet Storm Center agreed. On Friday, ISC researcher Swa Frantzen said, "It 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."

Already, Frantzen added, malicious Web site creators send exploits to visitors based on what browser and/or platform the surfer is using.

According to Kaspersky's research the Linux.Bi.a/Win32.Bi.a virus can infect either ELF binaries (Linux) or files with the ".exe" extension (Windows).