Xak Virus

 Virus Name:  Xak 
 V Status:    New 
 Discovery:   July, 1994 
 Symptoms:    .COM file growth; 
              decrease in total system & available free memory 
 Origin:      Unknown 
 Eff Length:  3,132 Bytes 
 Type Code:   PRhCK - Parasitic Resident .COM Infector 
 Detection Method:  F-Prot, IBMAV, ViruScan, NAV, NAVDX, AVTK, ChAV, 
                    NShld, IBMAV/N, NProt, NAV/N, AVTK/N, Innoc 
 Removal Instructions:  Delete infected files 
 General Comments: 
       The Xak virus was received in July, 1994.  Its origin or point of 
       isolation is unknown.  Xak is a memory resident infector of .COM 
       files, including COMMAND.COM. 
       When the first Xak 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 6,496 bytes.  Interrupts 1C and 21 will be 
       hooked by the virus in memory. 
       Once the Xak virus is memory resident, it will infect .COM programs 
       when they are executed.  Infected programs will have a file length 
       increase of 3,132 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 not be altered.  The following text strings are visible 
       within the viral code: 
        "This code, called Xak version  0012, is the  #### generation from" 
        "the original code of the same version number and was created by a" 
        "predecessor code on the  ## day of the month of  ## of the year" 
        " #### at  ## hours,  ## minutes, and  ## seconds." 
       Within the above text, the pound or number signs (#) will be numeric 
       values in the text which depend on the generation number of the 
       virus and the date and time the replication occurred. 

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