Some malware programs cause serious
problems such as destroying the system files, causing disruption to the
computer operation or gathering sensitive information while others may
only have a light impact such as redirecting websites to pornographic
content or annoying the users with pop-ups and banners.
In the normal routine, we have often
seen every malicious program being referred to as a virus, but this is
not correct! In fact, as mentioned earlier, there exists several
malicious programs where virus is one among them. Now, many of you may
be wondering to know what’s the difference between them. Well, this
article gives a detailed information on different types of malware that
exist, how they work and how they differ from each other:
Computer Virus:
As we all know, this is the type of
malware that has become highly popular and is one of the most widely
discussed topic in the field of computer security. A virus is just a
computer program that is designed to take unauthorized control of the
infected computer so as to cause harm to the system’s data or degrade
it’s performance.
Mode of operation:
Computer viruses operates by attaching
themselves to an already existing file or program and replicates itself
to spread from one computer to another. In most cases, they tend to
infect executable files that are parts of legitimate programs. So,
whenever the infected file is executed on a new computer, the virus gets
activated and begins to operate by further replication or causing the
intended damage to the system.
A virus cannot perform it’s task of
harming and replication unless it is allowed to execute. This is the
reason why viruses often choose an executable file as it’s host and get
attached to them. Viruses are mainly classified into two types:
Non-Resident Viruses:
This kind of virus will execute along with it’s host, perform the
needful action of finding and infecting the other possible files and
eventually transfers the control back to the main program (host). The
operation of the virus will terminate along with that of it’s host.
Resident Viruses: In
case of resident viruses, whenever the infected program is run by the
user, the virus gets activated, loads it’s replication module into the
memory and then transfers the control back to the main program. In this
case, the virus still remains active in the memory waiting for an
opportunity to find and infect other files even after the main program
(host) has been terminated.
Damages caused:
Viruses are known to cause destruction
of data and software programs. In some cases, a virus may do nothing
other than just replicating itself. However, they are responsible for
using a large portion of the system resources such as CPU and memory
which results in the performance degradation of the computer.
In order to stay protected from a virus infection, you may refer my other post on 12 tips to maintain a virus free computer.
Trojan horse:
A Trojan horse or simply called as
Trojan is a type of malicious program that disguises itself as something
that is legitimate or useful. The main purpose of a trojan is to gain
the trust of the user from the front end, so that it gets the permission
to be installed. But, from the back end, it is designed to grant
unauthorized control of the computer to the hacker.
Mode of operation:
A Trojan horse do not depend on the host
to carry out it’s operation. So, unlike a computer virus, it does not
tend to attach itself to other files. Trojans are often disguised as
video codecs, software cracks, keygens and other similar programs
downloaded from untrusted sources. So, one has to be careful about those
untrusted websites that offer free downloads.
One of the most poplar example is the DNSChanger
trojan that was designed to hijack the DNS servers of the victimized
computers. It was distributed by some of the rogue pornographic websites
as a video codec needed to view online content.
Damages caused:
Trojan horses are known to cause a wide
variety of damages such as stealing passwords and login details,
electronic money theft, logging keystrokes, modify/delete files, monitor
user activity etc.
Worms:
Worms are standalone computer programs
with a malicious intent that spread from one computer to another. Unlike
viruses, worms have the ability to operate independently and hence do
not attach themselves to another program.
Mode of operation:
Worms often use a computer network to
spread itself by exploiting the security vulnerabilities that exist
inside the individual computers. In most cases, worms are designed only
to spread without causing any serious change to the computer system.
Damage caused:
Unlike viruses, worms do not cause
damage to the system files and other important programs. However, they
are responsible for consuming the bandwidth thereby degrading the
performance of the network.
Spyware:
Spyware is a type of malicious software
that can collect information about the activities of the target computer
without the knowledge of it’s users. Spywares such as keyloggers are
often installed by the owner or administrator of the computer in order
to monitor the activities of the users. This can be a parent trying to
monitor his child, a company owner trying to monitor his employee or
someone trying to spy on his/her spouse.
Mode of operation:
Spywares are designed to operate in a
totally stealth mode so that it’s presence is completely hidden from the
users of the computer. Once installed, they silently monitor all the
activities on the computer such as keystrokes, web activity, IM logs
etc. These logs are stored secretly for later access or uploaded online
so that the installer of the spyware program can have access to them.
Damage caused:
Apart from monitoring, spywares do not
cause any damage to the computer. However, in some cases the affected
computer may experience degradation in it’s performance.
Adware:
Adware is a software program that
automatically renders advertisements to the users without their consent.
Most common examples are pop-ups, pop-unders and other annoying banner
ads. The prime reason behind the design of adware is to generate revenue
for it’s author.
Mode of operation:
Adwares are are often bundled up with
some of the free utilities such as a browser toolbars, video downloaders
etc. When such programs are installed, the adware may take over and
distract user activity by displaying annoying advertisements.
Damage caused:
Adware is harmless in most of the
occasions. However, some are known to contain spywares that are used to
monitor the surfing habits of users. This may pose a threat to the
privacy of the users.
