Python Virus

 Virus Name:  Python  
 V Status:    New 
 Discovery:   December, 1994 
 Symptoms:    .COM & .EXE growth; file date/time seconds = "40"; 
              decrease in total system & available free memory; 
              DOS CHKDSK file allocation errors 
 Origin:      Unknown 
 Eff Length:  1,142 - 1,603 Bytes (Approx) 
 Type Code:   PRhAK - Parasitic Resident .COM & .EXE Infector 
 Detection Method:  AVTK, Sweep, F-Prot, NAV, NAVDX, VAlert, ViruScan, 
                    Sweep/N, AVTK/N, NShld, NAV/N, NProt 
 Removal Instructions:  Delete infected files 
 General Comments: 
       The Python virus was received in December, 1994.  Its origin or 
       point of isolation is unknown.  Python is a polymorphic stealth 
       virus which infects .COM and .EXE files, including COMMAND.COM. 
       When the first Python infected program is executed, this virus 
       may install itself memory resident at the top of system memory 
       but below the 640K DOS boundary.  It does not always install 
       itself memory resident, and the system user may have to execute 
       an infected program several times in order for the virus to become 
       memory resident.  When resident, total system and available free 
       memory, as indicated by the DOS CHKDSK program from DOS 3.3, will 
       have decreased by 1,264 bytes.  Memory mapping utilities will not 
       indicate that any interrupts are hooked by this area of memory. 
       Once the Python virus is memory resident, it will infect .COM and 
       .EXE programs when they are executed.  Infected programs will have 
       a file length increase of approximately 1,142 to 1,603 bytes with 
       the virus being located at the end of the file.  The file length 
       increase, however, is hidden by the virus when memory resident.  The 
       program's date and time in the DOS disk directory listing will not 
       appear to be altered, though the seconds field will have been set to 
       "40".  The following text string is encrypted within the viral code: 
       Execution of the DOS CHKDSK program with the Python virus memory 
       resident will result in file allocation errors being indicated on 
       all infected files. 

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