Hard Days Virus

 Virus Name:  Hard Days 
 V Status:    Rare 
 Discovered:  December, 1992 
 Symptoms:    .COM file growth; file date/time changes; 
              decrease in total system & available free memory 
 Origin:      Unknown 
 Eff Length:  662 Bytes 
 Type Code:   PRhCK - Resident Parasitic .COM Infector 
 Detection Method:  AVTK, F-Prot, IBMAV, Sweep, ViruScan, 
                    NAV, NAVDX, VAlert, PCScan, ChAV, 
                    Sweep/N, NShld, Innoc, NProt, AVTK/N, IBMAV/N, 
                    LProt, NAV/N 
 Removal Instructions:  Delete infected files 
 General Comments: 
       The Hard Days virus was submitted in December, 1992.  Its origin or 
       point of isolation is unknown.  Hard Days is a memory resident 
       infector of .COM programs, including COMMAND.COM.  It bears some 
       similarity to the  Red Diavolyata  virus. 
       When the first Hard Days infected program is executed, the Hard Days 
       virus will install itself memory resident at the top of system 
       memory but below the 640K DOS boundary, hooking interrupt 21.  Total 
       system and available free memory, as indicated by the DOS CHKDSK 
       program, will have decreased by 960 bytes.  Interrupt 12's return 
       will not have been moved. 
       Once the Hard Days virus is memory resident, it will infect .COM 
       programs, including COMMAND.COM, when they are executed.  Infected 
       programs will have a file length increase of 662 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 infection occurred.  The following 
       text string can be found within the viral code in all Hard Days 
       infected programs: 
               "It's hard days night!" 

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