Virdem was the first file virus for MS-DOS.[1] It was written by Ralf Burger in 1986 as a demonstration program for the Chaos Computer Club conference. The virus spread by attaching itself to files with the .COM file extension. It is one of the oldest MS-DOS viruses.[2]
In December 1986, Burger distributed the virus at the Chaos Computer Club conference in Hamburg, Germany.[3] The virus could copy itself and attach that copy to any .COM files. Virdem was fairly harmless as it announces its presence clearly.[failed verification][4]