AIDS II Virus
Virus Name: AIDS II
Aliases: Companion Virus
V Status: Endangered
Discovery: April, 1990
Symptoms: Creates .COM files; melody; message
Eff Length: 8,064 Bytes
Type Code: SNA - Spawning Non-Resident .COM & .EXE Infector
Detection Method: ViruScan, NAV, F-Prot, AVTK, Sweep, IBMAV,
NAVDX, VAlert, PCScan, ChAV,
NShld, Sweep/N, Innoc, AVTK/N, NProt, IBMAV/N, NAV/N,
Removal Instructions: Delete corresponding .COM files
The AIDS II virus, or Companion virus, was isolated for the first
time in April 1990. Unlike other generic file infectors, the AIDS
II virus is the first known virus to employ what could be called a
"corresponding file technique" of infection so that the original
target .EXE file is never changed. The virus takes advantage of the
DOS feature where if a program exists in both .COM and .EXE form,
the .COM file will be executed.
The AIDS II virus does not actually infect .EXE files, instead it
stores a copy of the virus in a corresponding .COM file which will
be executed when the user tries to execute one of his .EXE files.
The .EXE file and the .COM file will both have the same base file
The method of infection is as follows: when an "infected" program
is executed, since a corresponding .COM file exists, the .COM file
containing the viral code is executed. The virus first locates an
uninfected .EXE file in the current directory and creates a
corresponding (or companion) .COM file with the viral code. These
.COM files will always be 8,064 Bytes in length with a file
date/time of the date/time of infection. The .EXE file is not
altered at all. After creating the new .COM file, the virus then
plays a melody and displays the following message:
"Your computer is infected with ...
Aids Virus II
- Signed WOP & PGT of DutchCrack -"
The AIDS II virus then spawns to the .EXE file that was attempting
to be executed, and the program runs without problem. After
completion of the program, control returns to the AIDS II virus. The
melody is played again with the following message displayed:
"Getting used to me?
Next time, use a Condom ....."
Since the original .EXE file remains unaltered, CRC checking
programs cannot detect this virus having infected a system.
One way to manually remove the AIDS II virus is to check the disk
for programs which have both an .EXE and a .COM file, with the .COM
file having a length of 8,064 bytes. The .COM files thus identified
should be erased.
The displayed text strings do not appear in the viral code.