4-days Virus

Virus Name: 4-days Aliases: V Status: New Discovery: July, 1994 Symptoms: .COM & .EXE growth; file date/time changes; decrease in total system & available free memory Origin: Unknown Eff Length: 1,358 - 1,372 Bytes Type Code: PRhAK - Parasitic Resident .COM & .EXE Infector Detection Method: F-Prot, IBMAV, AVTK, Sweep, ViruScan, NAV, NAVDX, VAlert, PCScan, AVTK/N, Sweep/N, IBMAV/N, NProt, NShld, NAV/N Removal Instructions: Delete infected files General Comments: The 4-days virus was received in July, 1994. Its origin or point of isolation is unknown. 4-days is a memory resident infector of .COM and .EXE files, including COMMAND.COM. When the first 4-days infected program is executed, the 4-days 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 1,360 bytes. Interrupt 21 will be hooked by the virus in memory. Also at this time, the virus will infect COMMAND.COM if it was not previously infected. Once the 4-days virus is memory resident, it will infect .COM and .EXE files when they are executed. Infected programs will have a file length increase of 1,358 to 1,372 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. The following text strings are visible within the viral code in all infected files: "COM EXE com exe OVL" "ALIEN 1.0 written by P.K. on April 93 Good Luck !!!"