Security vendor Kaspersky Labs has uncovered a proof-of-concept virus that is able to infect both Linux and Windows systems. The security company refers to the online pest as Virus.Linux.Bi.a/ Virus.Win32.Bi.a. 

While the virus is capable of infecting files on both platforms, it infects files only in the current directory. Most importantly, it does not cause any actual harm to infected systems and does not self-propagate.

The ability to infect Linux systems limits the virus in its attempt to cause harm, according to David Perry, global education director with antivirus vendor Trend Micro. 

Users need to manually download and open the file to become infected and, since Linux is mostly used on servers, few users on that operating system will pick up the virus.

"There would be more to gain by attacking Windows and Mac OS X rather than Windows and Linux because there are more desktops available on OS X," Perry told vnunet.com. 

"This is an interesting milestone, but no reason to sell the farm. Nobody has to stay up late tonight."

The code could spark the creation of more cross-platform viruses, however, as the author has, in a sense, blazed a new trail.

"This is written in an assembler so we know it's written by a programmer, as opposed to a lot of other [malware]. The gauntlet is down. Somebody has proof that they can write a virus for two operating systems," said Perry.

The virus appears to be written by a traditional malware author who is showing off his programming skills rather than creating malware for financial gain.

The virus leaves a text string in infected files that refers to the Immortal Riot, an online publication where virus authors posted proof-of-concept code between 1993 and 1996.