557 Virus

Virus Name: 557 Aliases: V Status: Rare Discovery: July, 1992 Symptoms: .EXE file growth; file date/time changes; decrease in total system and available free memory Origin: Unknown Eff Length: 557 - 566 Bytes Type Code: PRhE - Parasitic Resident .EXE Infector Detection Method: ViruScan, NAV, Sweep, AVTK, F-Prot, IBMAV, NAVDX, VAlert, PCScan, ChAV, NShld, Sweep/N, AVTK/N, NProt, NAV/N, IBMAV/N, Innoc, LProt Removal Instructions: Delete infected files General Comments: The 557 virus was received in July, 1992. Its origin or point of isolation is unknown. This virus is a memory resident infector of .EXE programs. When the first 557 infected program is executed, this virus will install itself memory resident at the top of system memory but below the 640K DOS boundary. Total system and available free memory, as indicated by the DOS CHKDSK program, will have decreased by 624 bytes. Interrupt 21 will be hooked by the 557 virus in memory. Once the 557 virus is memory resident, it will infect .EXE programs when they are executed. Infected programs will have a file length increase of 557 to 566 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 have been updated to the current system date and time when infection occurred. One text string occurs in all infected programs: "X[YZ]" The 557 virus doesn't appear to do anything but replicate.