MX-335 Virus

 Virus Name:  MX-335 
 V Status:    Rare 
 Discovery:   June, 1993 
 Symptoms:    .EXE file growth; file date/time changes; 
              decrease in total system & available free memory 
 Origin:      Unknown 
 Eff Length:  335 - 351 Bytes 
 Type Code:   PRhE - Parasitic Resident .EXE Infector 
 Detection Method:  F-Prot, AVTK, IBMAV, Sweep, ViruScan, 
                    NAV, NAVDX, VAlert, PCScan, ChAV, 
                    Sweep/N, AVTK/N, NShld, NAV/N, NProt, IBMAV/N, Innoc, 
 Removal Instructions:  Delete infected files 
 General Comments: 
       The MX-335 virus was submitted in June, 1993.  Its origin or point 
       of isolation is unknown.  MX-335 is a memory resident infector of 
       .EXE programs. 
       When the first MX-335 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 368 bytes.  Interrupt 21 will be 
       hooked by the virus in memory. 
       Once the MX-335 virus is memory resident, it will infect .EXE 
       programs when they they are executed.  Infected programs will have 
       a file length increase of 335 to 351 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 have been updated to the current 
       system date and time when the infection occurred.  The following 
       text string can be found starting in the 19th byte of all infected 

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