It is a harmless nonmemory resident parasitic virus. It searches for .EXE files and writes itself to the end of the file. Then the virus writes the data of random length to the end of the file, so the file length grows by random value when infected.
The virus gets the address of INT 12h, stores it and sets the INT 21h handles to INT 12h address. While infecting this virus calls to INT 12h instead of INT 21h.
