It is a dangerous memory resident parasitic virus. It hooks INT 21h and writes itself to the end of EXE files that are accessed. To detect its TSR copy ("Are you here?" call) the virus uses INT 21h call with AH=FAh, the memory resident code returns AH=0Dh - this is the reason to name this virus.
The virus has errors and may crash the system. On 23 and 24 of any month depending on the system time the virus displays the message in Russian (means "ASS"):
XXx XX xXX xXXXXXXXXXXx XXXXXXXXXXXx xXXXXXXXXXXX
xXXxXXxXXx XXx xXX XX XX XXx XX
XXXXXX XX XX XX XX XXXXXXXXXXXX
xXXxXXxXXx XXx xXX XX XX XXx xXX
XXx XX xXX xXXXXXXXXXXx XX XX XX XX
