About computer viruses Essay

Chapter ( 1 )


1.1 Introduction to Virus

Computer viruses are perceived as a menace to both concern and forces. A virus is a self-propagating piece of package that runs as an feasible plan on a mark machine. It is non, nevertheless, a stand-alone piece of package. It must piggyback itself on something else, such as a piece of electronic mail or other application plan, and is “installed” on a victim machine when the user accesses the host package. Some virus infection can be comparatively benign such as exposing a duologue box or it can be earnestly destructive, canceling ?les from a difficult thrust, doing a computing machine to bring up once more and once more, and so on. Some viruses are known to be polymorphous, intending that they can alter themselves as they propagate so that each transcript looks a spot different from all others.
There are three ways of virus fells itself from sensing:

  • Encrypts itself into deep symbols,
  • Alters the disc directory informations to counterbalance the extra virus bytes and
  • Uses stealth algorithms to airt disc informations.

Gun trigger events and direct onslaught are the common manners which cause a virus to detonate on a mark system. Most of the viruses operate in two stages:

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  • Infection Phase: Virus developers decide when to infect host system ‘s plans. Some infect each clip they are run and executed wholly whereas some virus codifications infect merely when users trigger them which include a twenty-four hours, clip, or a peculiar event.
  • Attack Phase: Some viruses have trigger events to trip and pervert systems while some viruses have bugs which replicate and execute activities like file omission, increasing session clip. They corrupt the marks merely after distributing wholly as intended by their developers.

1.2 Viruss Spreading and its Areas of Infection

Viruss are classified based on what they infect and how they infect. System Sector or Boot Virus are dispersed disc boot sectors and records. File Virus is dispersed executables in OS file system. Macro Virus infects paperss, spreadsheets and databases such as Microsoft Word, Excel and Access. Source Code Virus is overwrites or appends host codification by adding Trojan codification in it. Network Virus is spread itself via electronic mail by utilizing bid and protocols of computing machine web.
Virus authors can hold assorted grounds for making and distributing malware. Viruss have been written as research undertakings, buffooneries, hooliganism, to assail the merchandises of specific companies, to administer political messages, fiscal addition, individuality larceny, spyware, cryptoviral extortion etc. If the system acts in an unprecedented mode, that can surmise a virus onslaught. For illustration, procedures take more resources and are clip devouring nevertheless, non all bugs can be attributed to virus onslaughts.
There is a difference between general viruses and worms. A worm is a particular type of virus that can retroflex itself and utilize memory, but can non attach itself to other plans. A worm spreads through the septic web automatically but a virus does non.
When virus attacks the systems, plans take longer to lade than normal, computing machine ‘s difficult thrust invariably runs out of free infinite, files have strange names which are non recognizable, plans act unpredictably and resources are used up easy. Virus harm can be grouped loosely under Technical Attributes where trifles involved in the modeling and usage of virus causes harm due to miss of control, trouble in separating the nature of onslaught, draining of resources, presence of bugs and compatibility jobs.

Chapter ( 2 )


In computing machines, viruses can be transmitted as fond regards to an e-mail note, as downloads, or be present on a floppy or Cadmium. The immediate beginning of them we have received is normally incognizant that it contains a virus.

2.1 Three Main Classes of Viruss

  • File infectors: Some file infector viruses normally attach themselves to.COM OR.EXE plan files. Some can infect any plan file ( .SYS, .OVL, .PRG, and.MNU ) for which executing is requested. When the plan is loaded, the virus is besides loaded. Other file infector viruses arrive as wholly-contained plans or books sent as an fond regard to an e-mail note
  • System or boot-record infectors. These viruses infect feasible codification found in certain system countries on a disc. They attach to the DOS boot sector on floppies or the Master Boot Record on difficult discs. A typical scenario ( familiar to the writer ) is to have a floppy from an guiltless beginning that contains a boot disc virus. When your operating system is running, files on the floppy can be read without triping the boot disc virus. However, if you leave the floppy in the thrust, and so turn the computing machine off or recharge the operating system, the computing machine will look foremost in your A thrust, find the floppy with its boot disc virus, burden it, and do it temporarily impossible to utilize your difficult disc. ( Allow several yearss for recovery. ) This is why you should do certain you have a bootable floppy.
  • Macro viruses. These are among the most common viruses, and they tend to make the least harm. Macro viruses infect your Microsoft Word application and typically insert unwanted words or phrases.

2.2 Preventive steps against viruses

2.1.1 Anti-virus Software

As we know bar is better than remedy, it should non accept discs or plans without look intoing them foremost utilizing a current version of an anti-viral plan and should non go forth a floppy disc in the disc thrust longer than necessary. The best protection against a virus is to cognize the beginning of each plan or file loaded into the computing machine or unfastened from e-mail plan. Since this is hard, we can utilize anti-virus package that can test e-mail fond regards and besides look into all of files on a regular basis and take any viruses that are found. And besides, that package will give a warning message of new viruses. Unless the warning is from a recognized beginning, opportunities are good that the warning is a virus fraud. There are many anti-virus package sellers. Here is a list of some freely available anti-virus package for personal usage:

  • Kaspersky Anti-Virus
  • Norton Antivirus
  • ZoneAlram Extreme Security
  • AVG Free Edition
  • McAfee
  • Panda Active Scan

2.1.2 Proxy Firewall

A firewall is package that acts like a wall between computing machine and the Internet. Just like a existent firewall maintain fire from distributing from one country to another and attempts to maintain computing machine viruses from distributing organize the Internet onto a computing machine or web. Companies use firewalls to protect web resources from unauthorised forces to sensitive company information such as paysheet or forces records. Most of big concern administrations route their communications through a placeholder waiter which is a constituent of firewall. It screens all entrance and outgoing messages carefully by utilizing a assortment of testing techniques or domain name or IP reference. Even though some Operating Systems include personal firewalls, concern users should buy a hardware firewall that is constitutional one alternatively of personal firewall. It is because hardware firewalls stop invasions before they break in the computing machine.

Chapter ( 3 )


3.1 Local area network

A Local Area Network ( LAN ) can link computing machines and pressmans within a limited country such as an office. This LAN can associate in with other LANs via radio or web connectivity. Local Area Networks are widely used to portion resources and exchange information by linking personal computing machines and workstations. In a LAN, each host means single computing machine has its ain CPU with which it runs plans but it besides able to entree informations and devices anyplace on the LAN. This means that many users can portion informations information and expensive devices like optical maser pressmans. By directing electronic mail or engaging in chat session users can besides do usage of LAN to interact with each other. So, if one computing machine is infected with viruses in the LAN, it could easy be spread to all workstations.

3.2 Internet Network and Attack

Information transmitted over webs has much higher security hazards than it kept on the stand-alone computing machine. In a concern, one of the of import occupations of the web decision makers is taking steps to protect a web signifier security hazards. On the cyberspace, the security hazard is greater because if no cardinal decision maker is present. Every unprotected computing machine is easy attack by malware ( malicious package ) i.e. Viruss, Worms and Trojan Equus caballuss, which are plans that act without a user ‘s cognition and intentionally change the computing machine ‘s operations. To find if a web or computing machine is vulnerable to an cyberspace or web onslaught or necessitate aid about Internet security breaches, the companies and persons can reach or see the Web site for the Computer Emergency Response Team Coordination Center ( CERT/CC ) which is authorities funded Internet security research and development centre.

3.3 Treatments to LAN infected by virus

Proactive is better than reactive. Once a web or computing machine got infected by viruses, it will take times and money to retrieve back. All users in the web should cognize or educate the web and cyberspace security. The web decision maker should take following step on the LAN.

  • Use an updated anti-virus package.
  • Perform a virus scan at least one time in a hebdomad.
  • Scan all the e-mails before directing or having them.
  • Always scan the storage media before linking it to your computing machine system.
  • Keep your web browser and operating system up-to-date.

However, if the web or computing machine still gets affected by virus even after following the above steps, so it will necessitate to utilize advanced file recovery application to retrieve your lost informations. These Partition Recovery tools guarantee absolute recovery of all files and booklets after about all sorts of virus onslaughts.


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