Agena Virus

Virus Name: Agena Aliases: V Status: Rare Discovery: September, 1992 Symptoms: .COM & .EXE file growth; decrease in total system & available free memory Origin: Spain Eff Length: 723 - 738 Bytes Type Code: PRhAK - Parasitic Resident .COM & .EXE Infector Detection Method: ViruScan, F-Prot, Sweep, AVTK, IBMAV, NAV, NAVDX, VAlert, ChAV, NShld, Sweep/N, AVTK/N, NProt, Innoc, NAV/N, IBMAV/N Removal Instructions: Delete infected files General Comments: The Agena virus was discovered in Spain in September, 1992. Agena is a memory resident infector of .COM and .EXE programs, including COMMAND.COM. When the first program infected with the Agena virus is executed, the Agena 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 1,296 bytes. Interrupts 20 and 21 will be hooked by Agena in memory. Once the Agena virus is memory resident, it will infect .COM and .EXE programs, including COMMAND.COM, when they are executed. Infected programs will have a file length increase of 723 to 738 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. No text strings are visible within the viral code in infected programs. It is unknown what Agena may do besides replicate.