Malware is word derived from two other words Malicious and software. So, it can be defined as unidentified software which is designed to damage or infiltrate a computer system without being recognized by the owner of the system. This word is used by computer professionals to define some hostile, annoying and intrusive software’s which posses a threat to the users systems. Software is considered as malware if it consists of some code which possesses a threat to the users system. So this includes worms, computer virus, Trojan horses, Spyware, crimeware, root kits and other unwanted software’s. Malware can be considered as something which is not defective but, it can be said as a program consisting of harmful bugs which can modify or damage the content of users system. Usually free antivirus software applications will prove to be the most effective remedy.


In olden days most of the computer programs like internet worms or MS-DOS viruses were written to slow down the opponents systems, but today this malware programs is used for damaging users systems and creating data loss in them. With the evolution of internet, the demand for this malicious content increased. Most of the hackers started using this software for breaking into networks and stealing important data present in them. Here is an instance, which says about the effect caused by malware: In 2003, few hackers have created malicious software which can break into user systems and take control over users systems for black market exploitation. To keep your computer safe you will need free antivirus software programs installed. These infected computers, can be used to send spam emails to host data such as child pornography.

Later malware emerged in the form of Spyware. This consists of some programs which can monitor users browsing, redirect affiliate marketing revenues to Spyware creator and display illegal advertisements. This Spyware is a part of malware which is unlike a virus program. It does not spread like a virus and damage the files in the system. It will exploit the security features of the systems network and allows advertising programs to install unsolicited processes for exploiting the system.

The best known types of malware as mentioned previously consist of computer worms and viruses. Viruses spread on computers by infecting boot sectors and other executable programs of the system. They sometimes have payloads in them. These payloads will be responsible for performing other actions like stealing of data. Virus is essentially malware which needs a response of the user, but a worm does not need any response. It can automatically multiply itself and slowdown the whole system. Trojan horses and root kits consist of special types of malicious infection. Trojan horse consists of a hidden code, which does not affect the system but makes the security of the system weak. Trojan horse consists of a harmful payload which creates undesirable effects when the user clicks on it. Root kits often will be used by hackers to stay on the users system for long time. Root kits allow the hacker to hide the malware from the user’s network.

 They modify the operating system of the host and hide this program from the user. Root kits have an ability to hide the malware process from the list of processes available on the system. Originally root kit was called as a set of tools which will be installed by an attacker on a UNIX system. Some of these root kits have an ability to defend themselves. Take caution and be alert when using free antivirus software tools on your system. When a user finds and deletes them they do not get deleted, but get doubled causing more threat to the system.

Backdoor is a malware operation. In this method the normal authentication procedures will be bypassed by the hacker. These back doors created by hackers to get an illegal access to the users system. Most of the crackers use these backdoors to secure remote access to a computer. Backdoors can be used by infectious programs like Trojan horses and worms. Malicious programs usually will be created by hackers to make the zombie computers work for them. Some of the spammer viruses like my doom and so big will be used by spammers to send scam emails. These infected computers will most usually be used as proxies for sending scam emails.

Data stealing malware is a special type which acts as a web threat. This harmful threat cheats the users and steals the data. This steeled data will later be used for underground distribution. Content threats which fall under this category consist of screen scrapers, key loggers, adware, Spyware, bots and backdoors. Some of the popular data stealing infections available in the market or web at present include Legmir, Qhost, Bancos and Gator. Legmir is a Spyware which steals personal information like account name, password etc. Qhost is a Trojan horse, which modifies the hosts file and points it to a DNS server. When user opens bank sites, these programs open temporary duplicate accounts which register the user id and password. This will later be used by the hacker to steal the money from bank accounts. Bancos is an information stealer which waits for user access to bank accounts and spoofs the pages of bank websites and steal secret information. Gator is a Spyware which monitors the web surfing habits of users and uploads data onto servers so that pop ups come up in users system.

Some of the serious threats which the world faced because of these infections include: First threat was a massive identity theft related to U.S. Retailers. In this theft around 40million debit and credit card numbers were stolen. Monster Worldwide Inc’s data was stolen by a Trojan horse, which included 1.6 million records. A system is said to be vulnerable to malicious threats if has any one of these properties: Homogeneity, defects, over privileged users, over privileged code, unconfirmed code. Common tools for protection include free antivirus software packages.

Homogeneity- If more than one system is running on one single OS, hacking that OS will get the information belonging to all other systems. If more than one system contains errors then that system is said to be hacked easily. Some code can be transferred to the main server using things like CD-ROM, floppy disk and USB device. This malware hacks the server and also the systems connected to it. Over privileged users sometimes can be given privilege to modify the contents in the system.