"The Christmas Tree virus of 1987 attacked IBM mainframes through an international network. It used electronic mail services to send copies of itself to network users. It displayed a holiday message on the receiver\u2019s screen and then e-mailed itself to others. The virus spread like an electronic chain letter through many kinds of communication links, including satellites and ocean cables, reportedly infecting computers in over 130 countries. This virus caused both denial of services and system shutdowns."@en . . "Christmas Tree virus"@en . . . . "The Christmas Tree virus of 1987 attacked IBM mainframes through an international network. It used electronic mail services to send copies of itself to network users. It displayed a holiday message on the receiver\u2019s screen and then e-mailed itself to others. The virus spread like an electronic chain letter through many kinds of communication links, including satellites and ocean cables, reportedly infecting computers in over 130 countries. This virus caused both denial of services and system shutdowns."@en .