Kaczor Virus

Virus Name: Kaczor Aliases: Kaczor.4444 V Status: In the wild Discovered: July, 1996 Symptoms: .EXE file growth; file date/time seconds = "62"; decrease in available free memory; master boot sector altered; DOS CHKDSK file allocation errors Origin: Poland Eff Length: 4,444 Bytes Type Code: PRhEX - Parasitic Resident .EXE & MBR Infector Detection Method: F-Prot, AVTK, IBMAV, ViruScan, NAV, NAVDX, ChAV, Innoc, AVTK/N, IBMAV/N, NShld, NAV/N Removal Instructions: Delete infected files & Replace MBR General Comments: The Kaczor virus was received in July, 1996, and is reported to be "in the wild". It appears to be from Poland. Kaczor is a memory resident stealth, multi-partite virus which infected the system hard disk master boot sector as well as .EXE files. It appears to be at least slightly polymorphic as well. When the first Kaczor infected program is executed, this virus will become memory resident at the top of system memory but below the 640K DOS boundary, not moving interrupt 12's return. Available free memory, as indicated by the DOS CHKDSK program from DOS 5.0, will have decreased by 6,144 bytes. Interrupts 13 and 21 will be hooked by the virus in memory. Also at this time, the virus will infect the system hard disk master boot sector if it was not previously infected, resulting in any boot of the system from the system hard disk making the virus memory resident. Once the Kaczor virus is memory resident, it will infect .EXE files when they are executed, opened, or copied. Infected files will have a file length increase of 4,444 bytes, though this file length increase will be hidden by the virus when it is memory resident. The viral code will be located at the end of the file. 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 "62". The following text strings are encrypted within the viral code: "Zrobione." "Wersja" "Kodowanie" "Licznik HD" "K a c.z,o r!!t e s t" The DOS CHKDSK program will indicate file allocation errors on all infected files when this virus is memory resident.