# it-e-67 Can Graphics Files Be Infected with a Virus

For most types of graphics file formats currently available the answer is "no". A virus (or
worm, Trojan horse, and so forth) is fundamentally a collection of code (that is, a program) that
contains instructions which are executed by a CPU. Most graphics files, however, contain only
static data and no executable code. The code that reads, writes, and displays graphics data is
found in translation and display programs and not in the graphics files themselves. If reading or
writing a graphics file caused a system malfunction is it most likely the fault of the program
reading the file and not of the graphics file data itself.
With the introduction of multimedia we have seen new formats appear, and modifications to
older formats made, that allow executable instructions to be stored within a file format. These
instructions are used to direct multimedia applications to play sounds or music, prompt the user

for information, or display other graphics and video information. And such multimedia display
programs may perform these functions by interfacing with their environment via an API, or by
direct interaction with the operating system. One might also imagine a truly object-oriented
graphics file as containing the code required to read, write, and display itself.
Once again, any catastrophes that result from using these multimedia application is most
like the result of unfound bugs in the software and not some sinister instructions in the graphics
file data. Such "logic bombs" are typically exorcised through the use of testing using a wide
variety of different image files for test cases.
If you have a virus scanning program that indicates a specific graphics file is infected by
virus, then it is very possible that the file coincidentally contains a byte pattern that the scanning
programming recognizes as a key byte signature identifying a virus. Contact the author (or even
read the documentation!) of the virus scanning program to discuss the probability of the
mis-identification of a clean file as being infected by a virus. Save the graphics file, as the author
will most likely wish to examine it as well.
If you suspect a graphics file to be at the heart of a virus problem you are experiencing, then
also consider the possibility that the graphics file's transport mechanism (floppy disk, tape or
shell archive file, compressed archive file, and so forth) might be the original source of the virus
and not the graphics file itself.

1, catastrophe  [kə'tæstrəfi]
n. 大灾难；大祸；惨败

2, sinister  ['sinistə]
a. 不吉利的,凶恶的,左边的

3, exorcise  ['eksɔ:saiz]
vt. 驱邪；除怪

4, coincidentally  [kəu,insi'dentli]
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