Istanbul Virus

Virus Name: Istanbul Aliases: Istanbul.1349 V Status: New Discovered: May, 1995 Symptoms: .COM & .EXE growth; decrease in available free memory Origin: Turkey Eff Length: 1,349 - 1,363 Bytes Type Code: PRhAK - Parasitic Resident .COM & .EXE Infector Detection Method: F-Prot, ViruScan, AVTK, NAV, NAVDX, IBMAV, PCScan, ChAV, NShld, NAV/N, IBMAV/N, AVTK/N, LProt, Innoc 4.0+ Removal Instructions: Delete infected files General Comments: The Istanbul virus was received in May, 1995. It appears to be from Turkey. Istanbul is a memory resident infector of .COM and .EXE files, including COMMAND.COM. It does not infect very small files. When the first Istanbul infected program is executed, this virus will become memory resident at the top of system memory but below the 640K DOS boundary. Total available free memory, as indicated by the DOS CHKDSK program from DOS 5.0 will have decreased by approximately 12,304 bytes. Interrupt 21 will be hooked by the virus in memory. Once the Istanbul virus is memory resident, it will infect .COM and .EXE files, other than very small files, when they are executed. Infected files will have a file length increase of 1,349 to 1,363 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 not be altered. The following text string is visible within the viral code in all infected files: "Anti-Virus?? Written in the city of Istanbul (c)1993" It is unknown what the Istanbul virus may do besides replicate. Known variant(s) of Istanbul are: Istanbul.1312: Received in January, 1996, this is a 1,312 byte variant of the Istanbul virus described above. Its size in memory is 1,328 bytes, hooking interrupt 21. It infects .COM and .EXE files, including COMMAND.COM, whne they are executed. Infected files will have a file length increase of 1,312 to 1,326 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 not be altered. The following text strings are visible within the viral code in all infected files: "Written in the city of Istanbul (c)1993." "Installed" "SSSSSSSSSSSSSS" Origin: Turkey January, 1996.