Virus Name: Brain
Aliases: Pakistani, Pakistani Brain, Clone, Nipper
V Status: Common
Symptoms: Extended boot time; volume label change; resident-TOM;
three contiguous bad sectors (floppy only); BSC
Eff Length: N/A
Type Code: BRt - Resident Boot Sector Infector
Detection Method: ViruScan, F-Prot, AVTK, NAV, Sweep, IBMAV,
NAVDX, VAlert, PCScan, ChAV
Removal Instructions: MDisk, F-Prot, NAV, or
DOS SYS command
The Pakistani Brain virus originated in Lahore, Pakistan and infects
disk boot sectors by moving the original contents of the boot sector
to another location on the disk, marking those 3 clusters (6 sectors)
bad in the FAT, and then writing the virus code in the disk boot
One sign of a disk having been infected, at least with the original
virus, is that the volume label will be changed to "(c) Brain".
Another sign is that the label "(c) Brain" can be found in sector 0
(the boot sector) on an infected disk.
This virus does install itself resident on infected systems, taking
up between 3K and 7K of RAM. The Brain virus is able to hide from
detection by intercepting any interrupt that might interrogate the
boot sector and redirecting the read to the original boot sector
located elsewhere on the disk, thus some programs will be unable to
see the virus.
The original Brain virus only infected floppies, however variants to
the virus can now infect hard disks. Also, some variants have had
the "(c) Brain" label removed to make them harder to detect.
Known variants of Brain are:
Brain-B: (Hard Disk Brain/Houston virus) hard disk version.
Brain-C: Brain-B with the "(c) Brain" label removed.
Clone: Brain-C but restores original boot copyright label.
Clone-B: Clone virus modified to destroy the FAT after 5/5/92.
Nipper: Received from Spain in July, 1991, this variant does not
infect hard disks. The virus contains the following text
strings within the boot sector:
"Welcome to the Dungeon
(c) 1999 NIPPER SOCIEDAD GAMBERRISTICA
VIVA LA PIRATERIA.
Dedicated to the memories of ................."