Cupertino, US-based utilities software house Symantec Corp and UK-based software security specialist Unipalm have leapt onto the annual æChernobylÆ virus scare. The W95.CIH virus attacks Windows-based applications, infecting the memory of a computer and then moving into any files opened, hiding in empty spaces within files lest it show any size increases that would reveal it.

Symantec claims that its Norton anti-virus software can defeat the chernobyl virus, so called because it lies dormant, infiltrating applications malignly only on the 26th day in April, the anniversary of the nuclear power station explosion. The virus has one particularly nasty side-effect, says Wendy Hoey from Unipalm. It infects the basic input/output system (BIOS), overriding and corrupting sections of the embedded drives in a computer.