Ontario Virus

 Virus Name:  Ontario 
 V Status:    Common 
 Discovered:  July, 1990 
 Symptoms:    .COM & .EXE growth; decrease in system and free memory; hard 
              disk errors in the case of extreme infections 
 Origin:      Ontario, Canada 
 Eff Length:  512 Bytes 
 Type Code:   PRtAK - Parasitic Encrypted Resident .COM & .EXE Infector 
 Detection Method:  ViruScan, NAV, AVTK, F-Prot, Sweep, PCScan, 
                    IBMAV, NAVDX, VAlert, ChAV, 
                    NShld, Sweep/N, Innoc, NProt, AVTK/N, NAV/N, IBMAV/N, 
 Removal Instructions:  Delete infected files 
 General Comments: 
       The Ontario virus was isolated by Mike Shields in Ontario, Canada 
       in July, 1990.  The Ontario virus is a memory resident infector of 
       .COM, .EXE, and overlay files.  It will infect COMMAND.COM. 
       The first time a program infected with the Ontario virus is 
       executed, it will install itself memory resident above the top of 
       system memory but below the 640K DOS boundary.  Total system memory 
       and free memory will be decreased by 2,048 bytes.  At this time, 
       the virus will infect COMMAND.COM on the C: drive, increasing its 
       length by 512 bytes. 
       Each time an uninfected program is executed on the system with the 
       virus memory resident, the program will become infected with the 
       viral code located at the end of the file.  For .COM files, they 
       will increase by 512 bytes in all cases.  For .EXE and overlay 
       files, the file length increase will be 512 - 1023 bytes.  The 
       difference in length for .EXE and overlay files is because the 
       virus will fill out the unused space at the end of the last sector 
       of the uninfected file with random data (usually a portion of the 
       directory) and then append itself to the end of the file at the 
       next sector.  Systems using a sector size of more than 512 bytes 
       may notice larger file increases for infected files.  Infected 
       files will always have a file length that is a multiple of the 
       sector size on the disk. 
       In the case of extreme infections of the Ontario virus, hard disk 
       errors may be noticed. 
       See:   1024 SBC   Ontario 730   Ontario III 

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