Hope this helps.See especially the last paragraph.
CIH is a virus that infects the 32-bit Windows 95/98/NT executable files, but can function only under Windows 95/98 and ME. It does not function under Windows NT or Windows 2000. When an infectedprogram is run under Windows 95/98/ME, the virus becomes resident in memory. To remove the virus, do one of the following:
Although Windows NT system files can be infected, the virus cannot become resident or infect files on a computer running Windows NT or Windows 2000. The virus does not function under DOS, Windows 3.1, or on Macintosh computers. Once the virus is resident, the CIH virus infects other files when accessed.
As of April, 1999, three known, similar variants of this virus exist. CIH versions 1.2 and 1.3 have a payload that will trigger on April 26, commemorating Chernobyl, the Soviet nuclear disaster, which occurred on April 26, 1986. CIH version 1.4 has a payload that will trigger on the 26th of any month. The payloadsof all the versions of CIH are the same.
The first payload overwrites the hard disk with random data, starting at the beginning of the disk (sector 0) using an infinite loop. The overwriting of the sectors does not stop until the system has crashed. As a result, the computer will not boot from the hard disk or floppy disk. Also, the data that has been overwritten on the hard disk will be very difficult or impossible to recover. You must restore the data from backups.
The second payload tries to cause permanent damage to the computer. This payload attacks the Flash BIOS (a part of your computer that initializes and manages the relationships and data flow between the system devices, including the hard drive, serial and parallel ports, and the keyboard) and tries to corrupt the data stored there. As a result, nothing may be displayed when you start the computer. A computer technician would need to fix this.
