First PC-to-mobile virus flagged

A group of security researchers claims to have found the first virus that can jump to a mobile device after infecting a PC.

The malicious software, dubbed "Crossover", was sent anonymously to the Mobile Antivirus Researchers Association, the group said in a statement released on Monday. The virus is a proof-of-concept bug and was not released in the wild, meaning that it doesn't pose an actual risk for PC and device users.

The research group said: "Crossover is the first malware to be able to infect both a Windows desktop computer as well as a PDA running Windows Mobile for Pocket PC."

When executed, the virus checks what type of machine it is running on. If it is a Windows PC, it will jump to a handheld device as soon as it detects a connection using Microsoft's ActiveSync synchronisation software. When running on a portable OS, it will erase all the files in the "My Documents" folder and copy itself to the start-up folder.

The virus could also hurt the performance of the Windows PC because it re-creates itself each time the PC is started. This can mean a user will end up running so many copies that it bogs down the PC.

Malicious software was already able to jump from a smart phone to a PC. Security firm F-Secure last September found a Trojan horse that attempts to spread from smart phones to users' PCs, marking one of the first cases of virus "cross-sharing" between the two devices.

The Mobile Antivirus Researchers Association said it will make detailed analysis and the "Crossover" virus file available to antivirus companies and select security experts. F-Secure said on Tuesday on its blog that it hasn't seen a sample of Crossover yet.

Joris Evers writes for CNET News.com