Wednesday, F-Secure discovered a trojan for Symbian. Nothing new until they found out that the virus was capable to infect a Windows system too, when the user would have put the memory card of an infected cell phone into a PC.

SymbOS/Cardtrap.A is the trojan in question.

After he settles on the phone, Cardtrap.A copies two Windows worms (Win32/Padobot.Z and Win32/Rays) to the memory card of the phone. Padobot.Z is copied with autorun.inf file in attempt to start automatically if the card is inserted to PC using windows. Rays is copied with filename SYSTEM.EXE and same icon as the System folder, this is done as social engineering attempt so that user would click on Rays instead of System folder.
Luckily normal Windows systems doesn’t support autorun from a memory card, but still the risk is very high.

You can protect yourself by downloading F-Secure antivirus.