News

CIH May Return on Monday

• By Scott Bekker
• 04/23/1999

The companies are warning computer users to be on their guard against CIH, a hardware-attacking computer virus that wipes out the user's hard disk and overwrites the computer BIOS chip, making the computer unusable.

CIH is a family of computer viruses which infect Windows 95/98 programs. If an infected program is run, the virus will become active and begin to copy itself into other programs (EXE files) on your system. CIH can replicate quickly enough to infect hundreds of files on a system.

Normally, CIH simply spreads itself. But on certain trigger dates, it detonates its warhead. The warhead wipes out your hard disk, and then tries to overwrite the computer's BIOS chip. Once the BIOS is overwritten, you will be unable to use your computer at all. Repair involves physically removing the BIOS chip and replacing it with a fresh one. On some computers, the BIOS chip is not removable, so it can only be replaced by swapping the entire motherboard.

There are several variants of CIH, with different trigger conditions. The best known, and most widespread, variant will detonate on 26 April. Other variants detonate on 26 June, or even on the 26th of any month.

CIH spreads under Windows 95 and Windows 98. DOS and Windows 3.x cannot spread CIH because they cannot run Windows 95/98 programs. Windows NT cannot spread CIH because the virus uses programming tricks that do not work under NT. The virus can infect Windows NT programs, but such programs will no longer run, and will therefore not be infectious themselves.

Anti-virus vendors have been criticized as of late for, shall we say opportunistic, publicity practices of handling recent virus outbreaks to sell anti-virus software. Nevertheless, CIH is a real virus, and IT departments, at the very least, should be aware of it. – Thomas Sullivan