Security experts have downplayed the risk of what is reported to be the first virus that can infect both Windows- and Linux-based PCs.
W32.Winux, which was discovered by anti-virus firm Central Command, is neither spreading nor particularly destructive. Its main points of interest are the techniques it uses.
According to Central Command, W32.Winux is a non-memory resident virus which can replicate under Windows 95/98/Me/NT/2000 (Win32) and Linux systems and infects PE files (Windows executable) and ELF files (Linux executable) files.
The infection method used by the virus is basic. It searches for PE or ELF executable files and then calls an infection routine, which attempts to overwrite parts of the executable files it targets.
Quite how it might spread isn't clearly explained and Central Command says it has received only one report of the virus, which would tie in with the bug being emailed to them by the virus author himself.
Andre Post, a senior antivirus researcher at Symantec, said W32.Winux could only be spread by sharing files and described the risks from the bug as low. None of Symantec's customers have been affected by W32.Winux.
"The point of interest with W32.Winux is that it might give other virus writers ideas - and more malicious payloads might be developed," said Post.
According to David Millard, technical manager of Command Software (an anti-virus firm entirely unrelated to Central Command), there are fewer than 10 viruses that infect Linux systems; he said the bug should be treated as a "proof of concept" rather than anything more serious.
Alex Shipp, of MessageLabs, which scans its customers email for viruses, said W32.Winux is really two viruses rolled into one and it was hard to imagine it posing a particular risk, even to users who have a Windows PC with a Linux partition.
"W32.Winux has curiosity value but whether it makes it into the wild and infects anyone is doubtful," said Shipp, adding that the virus is also very easy to detect. ®