Cholera Virus

 Virus Name:  Cholera 
 Aliases:     Cholera.1497, Cholera.1497.A 
 V Status:    New 
 Discovery:   July, 1995 
 Symptoms:    .COM & .EXE growth; decrease in available free memory 
 Origin:      Unknown 
 Eff Length:  1,497 - 2,064 Bytes 
 Type Code:   PRhAK - Parasitic Resident .COM & .EXE Infector 
 Detection Method:  F-Prot, AVTK, VAlert, Sweep, IBMAV, NAV, 
                    NAVDX, ViruScan, ChAV, 
                    Sweep/N, AVTK/N, IBMAV/N, NAV/N, NProt, NShld, 
 Removal Instructions:  Delete infected files 
 General Comments: 
       The Cholera, Cholera.1497 or Cholera.1497.A, virus was received 
       in July, 1995.  Its origin or point of isolation is unknown. 
       Cholera is a memory resident infector of .COM and .EXE files, 
       including COMMAND.COM. 
       When the first Cholera 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. 
       Available free memory, as indicated by the DOS CHKDSK program from 
       DOS 5.0, will have decreased by 2,048 bytes.  Interrupts 08 and 21 
       will be hooked by the virus in memory. 
       Once the Cholera virus is memory resident, it will infect .COM and 
       .EXE files, including COMMAND.COM, when they are executed.  Infected 
       .COM files will have a file length increase of 1,497 bytes while 
       .EXE files will increase in size bye 2,052 to 2,064 bytes.  In both 
       cases, the virus will be located at the end of the file.  The 
       program's date and time in the DOS disk directory listing will not 
       be altered.  The following text string is visible within the viral 
       code in all infected programs: 
           "Cholera v1.0 by dr Hellraiser 94-02-03" 
       It is unknown what the Cholera virus may do besides replicating. 
       Known variant(s) of Cholera are: 
       Cholera.1497.B: Also received in July, 1995, this is a minor 
           variant of the Cholera virus described above.  It contains the 
           following text string: 
           "Cholera v2.0 by dr Fleischman 93-12-29" 
           System hangs may occur when infected programs are executed. 
           Origin:  Unknown  July, 1995. 

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