|Place of Origin||Japan|
|Infection Length||600 bytes|
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.
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.
- Japanese Christmas.653
- Japanese Christmas.722
- Japanese Christmas.Cookie
- Japanese Christmas.600.F
Kaspersky Labs. VirusList.com, Virus.DOS.Christmas.600
McAffee Threat Center. "Japanese Christmas".