Virus Name: Narcosis
V Status: New
Discovered: July, 1994
Symptoms: .COM & .EXE file growth; MBR and diskette boot sector altered;
decrease in total system & available free memory; system hangs;
beeping; unexpected system reboots
Eff Length: 1,431 Bytes
Type Code: PRhAK - Parasitic Resident .COM .EXE MBR & Boot Sector Infector
Detection Method: IBMAV, AVTK, Sweep, VAlert, PCScan, ViruScan,
PCScan, ChAV, NAV, NAVDX,
IBMAV/N, AVTK/N, Sweep/N, LProt, NShld, NAV/N, Innoc
Removal Instructions: Delete infected files, Replace MBR, DOS SYS diskettes
The Narcosis virus was received in July, 1994. Its origin or point of
isolation is unknown. Narcosis is a memory resident multi-partite
infector of the system hard disk master boot sector, diskette boot
sectors, .COM and .EXE files, including COMMAND.COM.
When the first Narcosis infected program is executed, this virus will
infect the system hard disk master boot sector. The virus keeps a
copy of the master boot sector at Side 0, Cylinder 0, Sector 2, and
a copy of its viral code starting a Side 0, Cylinder 0, Sector 3 for
three sectors. The virus becomes memory resident at the top of system
memory but below the 640K DOS boundary, hooking interrupts 13 and 21.
Once memory resident, the Narcosis virus will infect .COM and .EXE
programs when they are executed. Infected programs will have a file
length increase of 1,431 bytes, though the file length increase will
be hidden by the virus when it is memory resident. The virus 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
file date's year will have had 100 years added to it. The following
text strings are visible within the viral code in all Narcosis
"[Narcosis] (c) 1994 Evil Avatar"
The Narcosis virus infects .EXE files as though they are .COM files,
as a result, execution of programs over 64K in size will result in
the following message being displayed and the user being returned to
the DOS prompt:
"Program too big to fit in memory"
Unexpected system hangs, system reboots, or a loud, continuous
beeping may occur when infected programs are executed.