Number 6 Virus
Virus Name: Number 6
V Status: Rare
Discovered: April, 1993
Symptoms: .COM file growth;
decrease in total system & available free memory
Origin: The Netherlands
Eff Length: 631 Bytes
Type Code: PRhC - Parasitic Resident .COM Infector
Detection Method: AVTK, F-Prot, ViruScan, IBMAV, Sweep,
NAV, NAVDX, VAlert, PCScan, ChAV,
NShld, NProt, AVTK/N, Sweep/N, NAV/N, IBMAV/N, Innoc,
Removal Instructions: Delete infected files
The Number 6 virus was submitted in April, 1993, and appears to be
from The Netherlands. Number 6 is a memory resident infector of
.COM programs, but not COMMAND.COM. It may be related to the
Civil War virus.
When the first Number 6 infected program is executed, the Number 6
virus will install itself memory resident at the top of system
memory but below the 640K DOS boundary, not moving interrupt 12's
return. Total system and available free memory, as indicated by
the DOS CHKDSK program, will have decreased by 1,024 bytes.
Interrupts 12 and 21 will be hooked by the virus in memory.
Once the Number 6 virus is memory resident, it will infect .COM
programs, other than COMMAND.COM, when they are executed or opened
for any reason. Infected .COM programs will have a file length
increase of 631 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. The following text string is visible
within the viral code in all Number 6 infected programs:
"#6 Virus, Trident/The Netherlands 1992A"
It is unknown what Number 6 may do besides replicate.
See: Civil War