Japanese Christmas
Type File virus
Creator Unknown
Date Discovered 1st of September 1989
Place of Origin Japan
Source Language VBS/QBASIC?
Platform MS-DOS
File Type(s) COM
Infection Length 600 bytes
Reported Costs Unknown

Japanese Christmas is an early DOS file infector. It was widespread in Japan (and mostly confined to that country) in 1989-1990, with variants developed as late as 1992. This virus, although very primitive when compared to later DOS Viruses, utilises very similar techniques of infection. This virus is benign, and causes no damage to software or hardware other than the risk of corruption.


When a file infected with Japanese Christmas is executed, it will infect one DOS .com file in its directory, appending itself to the end of the file. It can infect all .com files, including COMMAND.COM. Infected files will be 600 bytes larger than their original size. The virus will not be memory-resident.

If an infected file is executed on December 25, the message "A merry christmas to you", will appear on the screen. It will flash and have an underline for about half the time it is displayed. After some time the message disappears, and will not appear again until another infected file is executed.



F-Secure, F-Secure Virus Information Pages, "Japanese Xmas".

Kaspersky Labs., Virus.DOS.Christmas.600

McAffee Threat Center. "Japanese Christmas".

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