CIH, also known as the Chernobyl virus, is a computer virus that targets computers running the Windows 9x family of operating systems. There are several variants, with different trigger dates that cause the virus to activate on different days, ranging from once a month to once a year. The most widespread variant first activated on April 26, 1999, causing widespread damage to hundreds of thousands of computers worldwide and resulting in hundreds of millions of dollars of losses. CIH is notorious for its destructive payload, which overwrites critical areas of a computer's hard drive, leaving the data inaccessible. On some systems, it also intentionally corrupts the system's flash BIOS firmware stored on the motherboard. This makes the computer unable to boot, leaving the computer unusable until the BIOS chip or the entire motherboard is replaced.
Outbreak of CIH computer virus
Outbreak of CIH computer virus.
On April 26, in the year 1999, Outbreak of CIH computer virus. This event is recorded as a Historical Events event in the history of April 26, one of 377 recorded events on this date across all of history.
Key Facts
- This event took place on April 26, 1999 (AD era).
- It is categorised as a Historical Events event in recorded history.
- Referenced in 1 Wikipedia article.
- Wikipedia source last updated on 5 April 2026.
On This Date in History 377
This article draws on content from Wikipedia, available under CC BY-SA 4.0.
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