Threats to Computer Security
15
It must be noted that these signs can arise from causes other than viruses. For
example, in the case of email, infected messages can be sent with your return
address but not from your computer.
There are also indirect indications that your computer is infected:
Your computer freezes or crashes frequently;
Your computer loads programs slowly;
You cannot boot up the operating system;
Files and folders disappear or their contents are distorted;
The hard drive is frequently accessed (the light blinks);
The web browser (e.g., Microsoft Internet Explorer) freezes or behaves
unexpectedly (for example, you cannot close the program window).
In 90% of cases, these indirect systems are caused by malfunctions in hardware
or software. Despite the low likelihood that these symptoms are indicative of in-
fection, a full scan of your computer is recommended (see 5.3 on pg. 50) if they
should manifest themselves.
1.5.
What to do if you suspect
infection
If you notice that your computer is behaving suspiciously…
1.
Don‟t panic! This is the golden rule: it could save you from losing impor-
tant data.
2. Disconnect your computer from the Internet or local network, if it is on
one.
3. If the computer will not boot from the hard drive (the computer displays
an error message when you turn it on), try booting in safe mode or with
the emergency Microsoft Windows boot disk that you created when you
installed the operating system.
4. Before doing anything else, back up your work on removable storage
media (floppy, CD/DVD, flash drive, etc.).
5. Install Kaspersky Anti-Virus, if you have not done so already.
6. Update databases and application modules (see 5.6 on pg. 52). If poss-
ible, download the updates off the Internet from a different uninfected
computer, for instance at a friend‟s, an Internet café, or work. It is better
to use a different computer since, when you connect an infected com-