Chaos Year Virus

 Virus Name:  Chaos Year 
 Aliases:     Chaos Year.1837 
 V Status:    Rare 
 Discovery:   April, 1994 
 Symptoms:    .COM & .EXE growth; DOS CHKDSK file allocation errors; 
              decrease in total system & available free memory; 
              file date/time seconds = "60" 
 Origin:      Unknown 
 Eff Length:  1,837 Bytes 
 Type Code:   PRhAK - Parasitic Resident .COM & .EXE Infector 
 Detection Method:  ViruScan, F-Prot, IBMAV, NAV, AVTK, Sweep, 
                    NAVDX, VAlert, PCScan, 
                    NProt, AVTK/N, NShld, Sweep/N, IBMAV/N, NAV/N 
 Removal Instructions:  Delete infected files 
 General Comments: 
       The Chaos Year, or Chaos Year.1837, virus was submitted in April, 
       1994.  Its origin or point of isolation is unknown.  This virus 
       is a memory resident infector of .COM and .EXE programs, including 
       COMMAND.COM, which exhibits some stealth characteristics.     
       When the first Chaos Year infected program is executed, this virus 
       will install itself memory resident at the top of system memory but 
       below the 640K DOS boundary, not moving interrupt 12's return.  Total 
       system and available free memory, as indicated by the DOS CHKDSK 
       program, will have decreased by 2,560 bytes.  Interrupt 21 will be 
       hooked by the virus in memory. 
       Once the Chaos Year virus is memory resident, it will infect .COM 
       and .EXE programs when they are executed.  Infected programs will 
       have a file length increase of 1,837 bytes with the virus being 
       located at the end of the file, though the file length increase will 
       be hidden when the virus is memory resident.  The program's date and 
       time in the DOS disk directory listing will appear to be unaltered, 
       but the seconds field will have been set to "60".  The following text 
       string is encrypted within the viral code: 
       Systems infected with the Chaos Year virus will find that the DOS 
       CHKDSK program will detect file allocation errors on all infected 
       files when the virus is memory resident.  It is unknown what else 
       Chaos Year may do. 

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