Zelentsov Virus

Virus Name: Zelentsov Aliases: Zelentsov.379 V Status: New Discovered: July, 1995 Symptoms: .COM file growth; decrease in total available free memory; file date/time changes Origin: Unknown Eff Length: 379 Bytes Type Code: PRhCK - Parasitic Resident .COM Infector Detection Method: F-Prot, AVTK, VAlert, Sweep, IBMAV, NAV, NAVDX, ViruScan, ChAV, Sweep/N, IBMAV/N, NAV/N, NProt, NShld, AVTK/N, Innoc 4.0+ Removal Instructions: Delete infected files General Comments: The Zelentsov virus was received in July, 1995. Its origin or point of isolation is unknown. Zelentsov is a memory resident infector of .COM files, including COMMAND.COM. When the first Zelentsov infected program is executed, this virus will install itself memory resident at the top of system memory but below the 640K DOS boundary, hooking interrupts 08 and 21. Available free memory, as indicated by the DOS CHKDSK program from DOS 5.0, will have decreased by 400 bytes. Interrupt 12's return will not have been moved. Once the Zelentsov virus is memory resident, it will infect .COM programs, including COMMAND.COM, when they are executed. Infected .COM files will have a file length increase of 379 bytes with the virus being located at the end of the file. The file'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 string is visible within the viral code: "Virus ZELENTSOV"