Reverse.A Virus

 Virus Name:  Reverse.A 
 Aliases:     Spider 
 V Status:    New 
 Discovery:   July, 1994 
 Symptoms:    .COM & .EXE growth; 
              decrease in total system & available free memory 
 Origin:      Unknown 
 Eff Length:  950 - 962 Bytes 
 Type Code:   PRhAK - Parasitic Resident .COM & .EXE Infector 
 Detection Method:  F-Prot, AVTK, IBMAV, ViruScan, Sweep, 
                    NAV, NAVDX, VAlert, PCScan, ChAV, 
                    NProt, AVTK/N, NShld, Sweep/N, IBMAV/N, NAV/N, LProt, 
                    Innoc 4.0+ 
 Removal Instructions:  Delete infected files 
 General Comments: 
       The Reverse.A virus was received in July, 1994.  Its origin or 
       point of isolation is unknown.  Reverse.A is a memory resident 
       virus which infects .COM and .EXE programs, including COMMAND.COM. 
       It is a fast file infector, spreading quickly on infected systems. 
       When the first Reverse.A 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 992 bytes.  Interrupt 21 will 
       be hooked by the virus in memory. 
       Once memory resident, this virus infects .COM and .EXE programs, 
       including COMMAND.COM, when they are executed or opened.  It does 
       not infect very small files.  Programs infected with Reverse.A will 
       have a file length increase of 950 to 962 bytes with the virus being 
       located at the end of the file.  In the case of COMMAND.COM, the virus 
       will overwrite a portion of the hex 00 area of the file, so there will 
       be no file length increase on infection.  The program's date and time 
       in the DOS disk directory listing will not be altered.  The following 
       text strings are encrypted within the viral code: 
               "Red Spider Virus created by Garfield from Zielowa Gora 
                in Feb 1993" 
       It is unknown what Reverse.A does besides replicate. 

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