As well as keeping your
anti-virus software up to date there are other ways in which you can
reduce the chances of virus infection inside your company. Below we list
some of the guidelines you might like to consider for safer computing.
Have a strict policy
in your organisation that downloading executables and documents from
the net is unacceptable, and that anything that runs in your
organisation has to be virus-checked and approved first. Unsolicited
executables/documents/spreadsheets etc. should not be run inside any
organisation. If you don't know that something is virus-free assume
it isn't. Ideally, staff should not be allowed to have anything they
don't actually need. However, you might want to consider providing a
selection of games/screen savers for staff to use which have been
virus-checked.
Block any unwanted
filetypes at the email gateway. Viruses often use filetypes such as
VBS, SHS, EXE, SCR, CHM and BAT to spread. It is unlikely that your
organisation will ever need to receive files of these types from the
outside. If this is the case Sophos recommends blocking all of them
at the email gateway - whether they are virus infected or not.
Some viruses attempt
to disguise their true executable nature by using "double
extensions". Files such as LOVELETTER.TXT.VBS or
ANNAKOURNIKOVA.JPG.VBS may appear to be harmless graphic or ASCII
text files at first glance at the file name. Sophos recommends
blocking any file which has "double extensions" from
entering an organisation.
Hoax
virus warnings and chain letter emails can be as disruptive as
viruses themselves. Aside from spreading misinformation and wasting
staff time and resources, it can be very embarrassing for your
organisation if an employee forwards these to contacts or customers.
A firm hoax policy such as this should be put in place:
"You shall not forward any virus warnings of any kind to anyone
other than <insert name of the department or staff member who
looks after anti-virus issues>. It doesn't matter if the virus
warnings have come from an anti-virus vendor or been confirmed by
any large computer company or your best friend. All virus warnings
should be sent to <insert name>, and <insert name>
alone. It is <insert name>'s job to send round all virus
warnings, and a virus warning that comes from any other source
should be ignored."
If you don't need
Windows Scripting Host, turn
it off.
Change the CMOS
bootup sequence so that rather than booting from drive A: if you
leave a floppy in your machine, you boot by default from drive C:
instead. This should stop all pure boot sector viruses (like Form,
CMOS4,
AntiCMOS,
Monkey,
etc) from infecting you. Should you need to boot from a floppy disk
the CMOS can easily be switched back.
Make regular backups
of important work and data, and check that the backups were
successful.
Keep an eye on Microsoft's
security bulletins. These warn of new security loopholes and
issues with Microsoft's software.
Produce a set of
guidelines and policies for safe computing and distribute them
amongst staff. Make sure that every employee has read and understood
them and that if they do have any questions they know who to speak
to. You may want to base these on the Sophos user guidelines below.
Use Rich Text Format
instead of DOC files which can harbour viruses. You can
automatically save all of your Word documents as RTF by selecting
Tools|Options|Save and choosing Rich Text Format as the default
format from the drop down menu.
Do not run, download
or forward any unsolicited executables, documents, spreadsheets,
etc. Anything that runs on your PC should be virus checked and
approved first.
Any email you weren't
expecting should be treated with suspicion, even if it comes from
someone you know. It is worth calling whoever sent it to you to
check that they intended to send you the email.
Do not open any files
with a double file extension, (e.g. iamavirus.txt.vbs). Under normal
circumstances you should never need to receive or use these.
Do not download
executables or documents from the internet. These are often used to
spread computer viruses.
Although JPG, GIF and
MP3 files cannot be infected with a virus, viruses can be disguised
as these file types. Jokes, pictures, graphics, screensavers and
movie files should be treated with the same amount of suspicion as
other file types.
If in doubt, always
ask your IT department for advice, do not open the file or email.
If you think you have
been infected with a virus inform your IT department immediately. Do
not panic or interrupt other users.
Any virus warnings or
hoaxes should be sent to the IT department who can confirm whether
or not it is genuine. Do not forward these warnings to anyone else;
unless you are signed up to an official virus alert service it is
unlikely to be a genuine warning.
If you have to work
at home ensure that you follow the same procedures there as you do
at work. Viruses can easily be brought into an organisation along
with work that has been done on a home PC.
Anti-virus software will
prevent the vast majority of viruses from entering an organisation but
it is not fool-proof. It is your responsibility to ensure that you don't
get infected with a computer virus.
