Unsnared Virus


 Virus Name:  Unsnared 
 Aliases:     Unsnared.814 
 V Status:    In the wild 
 Discovered:  July, 1996 
 Symptoms:    .EXE file growth; file date/time minutes = "13"; system hangs; 
              decrease in total system & available free memory 
 Origin:      Unknown 
 Eff Length:  814 Bytes 
 Type Code:   PRtE - Parasitic Resident .EXE Infector 
 Detection Method:  F-Prot, AVTK, IBMAV, ViruScan, PCScan, NAV, NAVDX, 
                    ChAV, 
                    Innoc, AVTK/N, IBMAV/N, NShld, NAV/N 
 Removal Instructions:  Delete infected Files 
 
 General Comments: 
       The Unsnared virus was received in July, 1996 and has been reported 
       to be "in the wild".  Its origin or point of isolation is unknown. 
       Unsnared is a memory resident infector of .EXE files. 
 
       When the first Unsnared infected program is executed, this virus 
       will install itself memory resident at the top of system memory 
       but below the 640K DOS boundary, moving interrupt 12's return. 
       Total system and available free memory, as indicated by the DOS 
       CHKDSK program from DOS 5.0, will have decreased by 1,024 bytes. 
       Interrupt 21 will be hooked by the virus in memory. 
 
       Once the Unsnared virus is memory resident, it will infect .EXE 
       files when they are executed.  Infected files will have a file 
       length increase of 814 bytes with the virus being located at the 
       end of the file.  The program's date in the DOS disk directory 
       listing will not be altered, but the minutes field in the time 
       will have been set to "13".  No text strings are visible within 
       the viral code. 
 
       System hangs frequently occur on infected systems when .EXE files 
       are executed. 

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