Virus.DOS.Obora.1558 or Obora is a virus that runs on MS-DOS.
Obora is a dangerous memory resident parasitic virus. It hooks onto INT 21h, and stays memory resident. Upon executing every 3rd file, the virus searches for .EXE files in the current directory, and writes itself to the end of the file. On Sundays, the virus, depending on the system time, also hooks onto INT 8 (timer), and scrolls the screen on each 185th timer tick. On the 22nd of any month, the virus corrupts the CMOS and displays the following message:
** MY NAME IS TROUBLe ** HELLO FROM " KETY " - CREATED BY KEVIN
The virus also contains the text strings:
KETY - POLAND!! PROSZE TU NIE GRZEBaC 96.02.12 TROUBLe - (c) by Kevin OBORa 96 V1.0 (c) by KEVIN