CHR-869 Virus

 Virus Name:  CHR-869 
 V Status:    Rare 
 Discovery:   March, 1993 
 Symptoms:    .COM & .EXE growth; file date/time changes; "#" character 
              displayed; decrease in total system & available free memory; 
              program execution failure 
 Origin:      Unknown 
 Eff Length:  869 - 1,348 Bytes 
 Type Code:   PRhA - Parasitic Resident .COM & .EXE Infector 
 Detection Method:  Sweep, AVTK, F-Prot, IBMAV, ViruScan, 
                    NAV, NAVDX, VAlert, PCScan, ChAV, 
                    Sweep/N, NShld, AVTK/N, NProt, IBMAV/N, Innoc, NAV/N, 
 Removal Instructions:  Delete infected files 
 General Comments: 
       The CHR-869 virus was submitted in March, 1993.  Its origin or point 
       of isolation is unknown.  CHR-869 is a memory resident infector of 
       .COM & .EXE programs, but not COMMAND.COM. 
       When the first CHR-869 infected program is executed, the CHR-869 
       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 3,120 bytes.  Interrupt 12's return 
       will not be moved. 
       Once memory resident, the CHR-869 virus will infect .COM and .EXE 
       programs, other than COMMAND.COM, when they are executed.  Infected 
       .COM programs will have a file length increase of 869 bytes.   
       Infected .EXE programs will have a file length increase of up to 
       1,348 bytes.  In both cases, the virus will be located at the end of 
       the infected 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.  No text strings are visible within 
       the CHR-869 viral code in infected programs. 
       Systems infected with the CHR-869 virus will notice that when the 
       virus is memory resident, a "#" character will be displayed on the 
       system monitor whenever a program is executed. 

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