software are computer programs that attempt to identify,
neutralize or eliminate malicious software. The term "antivirus"
is used because the earliest examples were designed exclusively
to combat computer viruses; however most modern antivirus
software is now designed to combat a wide range of threats,
including worms, phishing attacks, rootkits, trojan horses
and other malware. Antivirus software typically uses two
different approaches to accomplish this:
files to look for known viruses matching definitions in
a virus dictionary, and identifying suspicious behavior
from any computer program which might indicate infection.
The second approach is called heuristic analysis. Such analysis
may include data captures, port monitoring and other methods.
commercial antivirus software uses both of these approaches,
with an emphasis on the virus dictionary approach. Some
people consider network firewalls to be a type of antivirus
software, however this is not correct.
the virus dictionary approach, when the antivirus software
looks at a file, it refers to a dictionary of known viruses
that the authors of the antivirus software have identified.
If a piece of code in the file matches any virus identified
in the dictionary, then the antivirus software can take
one of the following actions:
Attempt to repair the file by removing the virus itself
from the file.
Quarantine the file (such that the file remains inaccessible
to other programs and its virus can no longer spread)
Delete the infected file.
To achieve consistent success in the medium and long term,
the virus dictionary approach requires periodic (generally
online) downloads of updated virus dictionary entries. As
civically-minded and technically-inclined users identify
new viruses "in the wild", they can send their
infected files to the authors of antivirus software, who
then include information about the new viruses in their
antivirus software typically examines files when the computer's
operating system creates, opens, closes, or e-mails them.
In this way it can detect a known virus immediately upon
receipt. Note too that a System Administrator can typically
schedule the antivirus software to examine (scan) all files
on the computer's hard disk on a regular basis.
Issues of concern :
regular appearance of new malware is certainly in the financial
interest of vendors of commercial antivirus software, but
there is no evidence of collusion.
antivirus software can considerably reduce performance.
Users may disable the antivirus protection to overcome the
performance loss, thus increasing the risk of infection.
For maximum protection, the antivirus software needs to
be enabled all the time — often at the cost of slower
is important to note that one should not have more than
one memory-resident antivirus software solution installed
on a single computer at any given time. Otherwise, the computer
may be crippled and further damaged.
is sometimes necessary to temporarily disable virus protection
when installing major updates such as Windows Service Packs
or updating graphics card drivers.Active antivirus protection
may partially or completely prevent the installation of
a major update.
When purchasing antivirus software, the agreement may include
a clause that your subscription will be automatically renewed,
and your credit card automatically billed at the renewal
time without your approval. For example, McAfee requires
one to unsubscribe at least 60 days before the expiration
of the present subscription.In that case, the subscriber
may contest the charges with the credit card issuer, but
this recourse is likely to fail if in fact the subscriber
had authorised such a "continuous payment authority".
Norton Antivirus also has a default setting that includes
the automatic renewal of your subscription.
Some antivirus programs are actually spyware masquerading
as antivirus software. It is best to double-check that the
antivirus software which is being downloaded is actually
a real antivirus program.
Some commercial antivirus software programs contain adware.
For example, the home/small business version of CA Anti-Virus
2008 displays an advert for CA products whenever the desktop
is unlocked after a period of inactivity.
Most widely-accepted antivirus programs often do not detect
newly-created viruses. This can be verified by making a
program with destructive code in a language like C++.
Anti-virus manuafacturers have been criticised for fear
mongering by exaggerating the risk that virus pose to consumers.
from the desktop and laptop world have migrated to mobile
devices. Antivirus vendors are beginning to offer solutions
for mobile handsets. These devices present significant challenges
for antivirus software, such as:
memory constraints, and
definitions and new signature updates to these mobile handsets.
Mobile handsets are now offered with a variety of interfaces
and data connection capabilities. Consumers should carefully
evaluate security products before deploying them on devices
with a small form factor.
that are hardware-based, perhaps USB devices or SIM-based
antivirus solutions, might work better in meeting the needs
of mobile handset consumers. Technical evaluation and review
on how deploying an antivirus solution on cellular mobile
handsets should be considered as scanning process might
impact other legitimate applications on the handheld.
solutions with antivirus integrated on the small memory
footprint might provide a basic solution to combat malware/viruses
in protecting PIM and mobile user data. Solutions based
on USB and Flash memory allow the user to swap and use these
products with a range of hardware devices.