VirusTrap creates two
15kb test files
(result.exe and
result.com).
The theory is that if
any viruses are
running on your
computer,
running these test
files should be
enough to infect
result.exe/com
with that virus -
trapping it for
analysis.
VirusTrap will 
alert you if either
the filesize,
modification date,
or checksum values
(internal data) 
have changed
after the execution
of the files.