CIH (computer virus)

CIH, also known as Chernobyl or Spacefiller, is a Microsoft Windows 9x computer virus that first emerged in 1998. Its payload is highly destructive to vulnerable systems, overwriting critical information on infected system drives and, in some cases, destroying the system BIOS. The virus was created by Chen Ing-hau (陳盈豪, pinyin: ''Chén Yíngháo''), a student at Tatung University in Taiwan. It was believed to have infected sixty million computers internationally, resulting in an estimated (|USD}}) in commercial damages.

Chen claimed to have written the virus as a challenge against bold claims of antiviral efficiency by antivirus software developers. Chen stated that after classmates at Tatung University spread the virus, he apologized to the school and made an antivirus program available for public download. Weng Shi-hao (翁世豪), a student at Tamkang University, co-authored with the antivirus program. Prosecutors in Taiwan could not charge Chen at the time because no victims came forward with a lawsuit. Nevertheless, these events led to new computer crime legislation in Taiwan.

The name "Chernobyl Virus" was coined sometime after the virus was already well known as CIH and refers to the complete coincidence of the payload trigger date in some variants of the virus (actually the virus creation date in 1998, to trigger exactly a year later) and the Chernobyl disaster, which happened in the Soviet Union on April 26, 1986.

The name "Spacefiller" was introduced because most viruses write their code to the end of the infected file, with infected files being detectable because their file size increases. In contrast, CIH looks for gaps in the existing program code, where it then writes its code, preventing an increase in file size; in that way, the virus avoids detection. Provided by Wikipedia