Number 6 Virus

 Virus Name:  Number 6 
 V Status:    Rare 
 Discovered:  April, 1993 
 Symptoms:    .COM file growth; 
              decrease in total system & available free memory 
 Origin:      The Netherlands 
 Eff Length:  631 Bytes 
 Type Code:   PRhC - Parasitic Resident .COM Infector 
 Detection Method:  AVTK, F-Prot, ViruScan, IBMAV, Sweep, 
                    NAV, NAVDX, VAlert, PCScan, ChAV, 
                    NShld, NProt, AVTK/N, Sweep/N, NAV/N, IBMAV/N, Innoc, 
 Removal Instructions:  Delete infected files 
 General Comments: 
       The Number 6 virus was submitted in April, 1993, and appears to be 
       from The Netherlands.  Number 6 is a memory resident infector of 
       .COM programs, but not COMMAND.COM.  It may be related to the 
       Civil War virus. 
       When the first Number 6 infected program is executed, the Number 6 
       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 1,024 bytes. 
       Interrupts 12 and 21 will be hooked by the virus in memory. 
       Once the Number 6 virus is memory resident, it will infect .COM 
       programs, other than COMMAND.COM, when they are executed or opened 
       for any reason.  Infected .COM programs will have a file length 
       increase of 631 bytes with the virus being 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 Number 6 infected programs: 
               "#6 Virus, Trident/The Netherlands 1992A" 
       It is unknown what Number 6 may do besides replicate. 
       See:   Civil War 

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