DOSVer Virus

Virus Name: DOSVer Aliases: 2062 V Status: Rare Discovered: August, 1993 Symptoms: .COM & .EXE growth; file date/time seconds = 60; decrease in total system & available free memory; DOS CHKDSK file allocation errors Origin: Unknown Eff Length: 2,062 Bytes Type Code: PRhAK - Parasitic Resident .COM & .EXE Infector Detection Method: AVTK, F-Prot, Sweep, ViruScan, IBMAV, NAV, NAVDX, VAlert, PCScan, ChAV, AVTK/N, NShld, Sweep/N, NProt, NAV/N, IBMAV/N, Innoc Removal Instructions: Delete infected files General Comments: The DOSVer virus was received in August, 1993. Its origin or point of isolation is unknown. DOSVer is a memory resident infector of .COM and .EXE programs, including COMMAND.COM. When the first program infected with the DOSVer virus 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 3,072 bytes. Interrupt 21 will be hooked by the virus. Once the DOSHunter virus is memory resident, it will infect .COM and .EXE ograms, including COMMAND.COM, when they are executed. Infected programs will have a file length increase of 1,666 bytes with the virus being located at the end of the file. The file length increase will be hidden by the virus when it is memory resident. The program's date and time in the DOS disk directory listing will have been altered so that the seconds field is set to "60". As a result, the file time may "disappear" from some files in the DOS disk directory listing. No text strings are visible within the viral code. Systems infected with the DOSVer virus may notice that the DOS CHKDSK program will return file allocation errors on all infected programs.