Romanian virus writer Dan Dumitru Ciobanu has been charged with unleashing a low-risk variant of the prolific MSBlast worm, dubbed MSBlast.F. The 24-year-old now faces up to 15 years' imprisonment.

Earlier this month, US teenager Jeffrey Lee Parson was released on bail after being charged with creating the MSBlast.B virus. Ironically, the author of the original and most damaging worm, MSBlast.A, still hasn't been found.

Altered versions of original viruses are extremely common and, according to antivirus experts, are far easier to create, which may be a reason why the original and perhaps more experienced writer still hasn't been named.

Ciobanu allegedly implemented the worm within the computer network of Romania's Iasi technical university. Antivirus specialist BitDefnder tracked down the author by his nickname, Copywrong, which appeared as a copyright name on all his work.

Authorities have removed two computers from Ciobanu's home and workplace and these are currently being analysed.

An antidote for MSBlast can be downloaded free of charge here.