Issue:
You want to
know about what kind of viruses can affect AutoCAD® and how to avoid them.
Solution:
The
two main types of viruses that can affect AutoCAD are VBA macros embedded
in drawing files and AutoLISP that runs automatically when a drawing is opened.
VBA Macro
Viruses
+AutoCAD installations have included VBA since AutoCAD 2000, making it possible to embed
VBA projects into drawing files. Once it is part of a drawing, a macro can
become active when the drawing is loaded. If that drawing is shared with
others, the macro has the potential to affect any computer on which it is
active. VBA macros are capable of manipulating your drawing data, accessing
your hard drive and registry, and even calling Windows API methods.
AutoLISP-based
Viruses
An
AutoLISP-based virus typically occurs via an AutoLISP file that runs
automatically when a drawing is opened. Such startup AutoLISP files include:
- acaddoc.lsp (e.g. acad2013doc.lsp) :
An Autodesk-provided file that runs every time a drawing is opened
- acad.lsp (e.g.acad2013.lsp) : An
Autodesk-provided file that runs once when AutoCAD is launched
- acaddoc.lsp : A user-created file that runs every time a drawing is
opened
- acad.lsp : An older-style file that runs once when AutoCAD is
launched
The primary
way you would get an AutoLISP-based virus would be through one of these
files. Typically, someone receives a .zip file or an archive
containing drawing files and one of these starts up AutoLISP files. When the
user extracts the archive to a folder and loads one of the drawings, the
included AutoLISP file is also loaded. That’s all it takes to initiate the
virus. Once this rogue file is loaded, it will execute its contents.
Don’t
underestimate the power of AutoLISP. Not only is it an extremely powerful
programming language for AutoCAD, but it is also capable of
- Executing
AutoCAD commands
- Running
VBA macros
- Executing
Windows apps using the (startapp) method
- Creating,
modifying, and deleting files on your computer
- Providing
full access to your Windows registry
How to Avoid
Viruses in AutoCAD 2013:
Service Pack
1 for AutoCAD 2013 includes new security options that help prevent malware and
viruses. Details can be found in the following document:
AutoLISP and VBA Security Controls in AutoCAD 2013 SP1
How to Avoid
Viruses in AutoCAD versions prior AutoCAD 2013:
Most leading
antivirus packages are aware of the most common AutoLISP viruses and will
quarantine the AutoLISP files when detected. You can also decrease your odds of
getting one of these viruses by developing the following habits:
Never
blindly extract an archive without checking its contents
AutoLISP-based
viruses usually get into a system because they accompany other files. When you
receive an archive (.zip, .rar, etc.), always inspect the
contents before unpacking them onto a network or local drive. Be wary of
archives that also include executables (.exe), ObjectARX files (.arx),
or AutoLISP or VBA files.
Never run an
unknown AutoLISP file or VBA macro without inspecting it first
There are
many useful VBA and AutoLISP files available for download and shared by users
and programmers all over the world. Most of these are probably fine, but if you
don’t know where a file came from, you shouldn’t assume it is safe. VBA and
AutoLISP are powerful languages that are capable of operations that will affect
more than just the current drawing. Unless you are completely confident about
the origin of a file and its creator, it’s worth the extra time to inspect the
file before using it.
Enable the
macro virus protection in AutoCAD
Anticipating
the potential for problem macros, AutoCAD software has long included an option
to warn you when opening a drawing or project file that includes embedded
macros. From that warning dialog box, you can disable the macros before
they are able to execute. The warning dialog box is enabled by default in
AutoCAD; if, for any reason, this dialog display becomes disabled, it can be
turned back on by running the VBARUN command, choosing the Options button, and
checking “Enable macro virus protection.” This setting will be saved in the
current profile.
By following
these tips and using a little diligence and common sense, you can easily avoid
introducing viruses into your AutoCAD work environment.
AutoCAD Versions: 2008;2009;2010;2011;2012;2013
Next to read:
AutoCAD File Corruption
This document contains content adapted from the Autodesk® Knowledge Network, available under Attribution-NonCommercial-No Derivative Works. Copyright © Autodesk, Inc.
