Dichotomy Virus

 Virus Name:  Dichotomy 
 V Status:    New 
 Discovered:  September, 1994 
 Symptoms:    .COM & .EXE growth; file date/time seconds = "62"; 
              decrease in total system & available free memory; 
              system hangs 
 Origin:      Unknown 
 Eff Length:  863 Bytes 
 Type Code:   PRhAK - Parasitic Resident .COM & .EXE Infector 
 Detection Method:  ViruScan, F-Prot, AVTK, Sweep, IBMAV, 
                    NAVDX, VAlert, NAV, PCScan, ChAV, 
                    IBMAV/N, NShld, AVTK/N, Sweep/N, NProt, NAV/N, LProt, 
                    Innoc 4.0+ 
 Removal Instructions:  Delete infected files 
 General Comments: 
       The Dichotomy virus was received in September, 1994.  Its origin or 
       point of isolation is unknown.  Dichotomy is a memory resident 
       infector of .COM and .EXE files, including COMMAND.COM. 
       When the first Dichotomy 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 1,072 bytes.  Interrupt 21 will be 
       hooked by the virus in memory. 
       Once the Dichotomy virus is memory resident, it will infect .COM and 
       .EXE files when they are executed.  Infected programs will have a file 
       length increase of 863 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 appear to be altered, though the seconds field will 
       have been set to "62".  The following text strings are visible within 
       the viral code in all Dichotomy infected programs: 
               "(c) 1994 Evil Avatar" 
       The Dichotomy virus infects .EXE files as though they are .COM files. 
       As a result, system hangs may occur when infected .EXE programs are 

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