The Three Common Computer Viruses Computer Science Essay

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There are commonly three types of virus. Firstly a worm is a computer program that invades computer on a network, replicates itself to prevent deletion, and cause interference with the host's computer's operation. Secondly Trojan horse is a program that contains a hidden function that causes damage to other programs. Finally file infector is a computer program modifies or deletes other files.

Computer virus can be spread through the following three channels. Through floppy disk, networks or internet. Through diskette infected files that are stored will transmit when opened on a uninfected computer. Network viruses spread extremely fast to all workstations in the network once the infected files are being shared via the network. Viruses can also spread through the internet, example infected web pages, unknown e-mails and attachment from e-mails. The host's computer will be infected with the same virus, or even mutate to a different strain, just like the bird flu incident.

Viruses can damage system areas of hard disks or diskette. It also corrupts executable programme and multiple files sizes. Some viruses will display weird messages, while others may trick you into believing that your keyboard of floppy disk drive or any other hardware or software is defective. Malicious viruses can erase files and reformat hard disk.

To prevent your computer from getting infected, preventive measures are to be taken. Make backup copies of important files and programme regularly. Start the computer from the hard disk. It is very important that you DO NOT INSERT your diskette or compact disk into the computer whenever you START the computer system. Write protect your disks if necessary. Install an anti-virus programme to detect and 'kill' virus. Updated the virus definition for your anti-virus programme regularly. Scan your hard disk for viruses periodically. Scan new soft ware for virus before installing them. Scan all disks from external sources before using them on your personal computer.

If the LAN network is infected the possible treatments for it is, first thing to do is to shut down the network temporality upon detection of the virus. This is to ensure that the infection of the virus stop spreading, and doing more wide spread damage to the corporate files and information kept in the network drive. A virus scan is then done on the network, to keep the files in the network clean and safe.

The next step is to find the infected areas and quarantine them, by disconnecting the cable of the individual workstations from the network. Doing this will keep the infection of the virus under control and contained.

Resuming of the network for other workstations comes next, this is for the corporate to resume to its normal working schedule. To destroy the virus infection, a virus scans with an updated virus definition will do the job.

The last thing left to do now is to connect the affected workstations back to the network. To ensure that there are no more traces of the virus, virus scan need to be done on the other unaffected workstations, and on the network once again.

To keep the virus away from your company's LAN network, invest in a good anti-virus tool specifically designed for LAN networks. On top of that, updating of the virus definition need to be done regularly, and it is also recommended to do a virus scan on all the workstations and also on the network weekly. As mentioned above outside personal computer the major cause of an infection, employees are best not to connect their personal computers to the corporate LAN network. Doing this will ensure the corporate LAN network to run smoothly.

One may also prevent the damage done by viruses by making regular backups of data, that are either kept unconnected to the system, read-only or not accessible for other reasons, such as using different file systems. This way, if data is lost through a virus, one can start again using the backup. If a backup session on optical media like CD and DVD is closed, it becomes read-only and can no longer be affected by a virus. Likewise, an Operating System on a bootable can be used to start the computer if the installed Operating Systems become unusable. Another method is to use different Operating Systems on different file systems. A virus is not likely to affect both. Data backups can also be put on different file systems.

Corporate LAN (local area network) network is under more attacks as outside PCs are brought in, or the external users connect via VPN connection. In each case, security is compromised as those PCs may not have sufficient patches applied, or infected by viruses. There are 2 solutions for LAN security improvement.

Quarantine Network

PCs brought in from outside can be a source of virus/work infection or corporate data leak. A separate VLAN is created to quarantine the unidentified PCs. The PCs are then scanned according to the security policy and allowed to connect to the corporate LAN if tested to be fine.

Virus Protection Gateway

Traditional anti-virus technologies are unable to detect the network viruses and prevent the mass infection within LAN network. Network administrators are thus tasked to prevent the virus infection, stop distribution and improve overall security and also defend the network from network viruses.

To create a separate network for computers that is brought in. A viewing network is build to quarantine external PCs brought in by employees and external personnel. This will prevent unintended connections to the core network, keeping out viruses and restricting access to internal resources (internal application server and file server).

Quarantine Network

Security status from each PC is retrieved(OS security patch level, Anti-Virus pattern file version, etc.). The status is then matched with security policy to determine whether the PC can connect to the corporate LAN or the quarantine LAN.

Outside PCs connected via VPN are scanned as well.

PCs violating the security policy are automatically redirected to Agent installation URL, Windows Update URL, virus scan server and asked to remedy the violations. Repaired PCs are then allowed to connect to the corporate VLAN.

Some example policies are:

OS security patch level

Process status on particular application

Status on virus scan software such as Symantec, McAfee. Versions on virus definitions.

Network configuration on a client PC

Registry information on a client PC

Virus Protection Gateway solution achieve real-time prevention of network work packets, auto update anti-virus pattern files, shut down the network connectivity from vulnerable PCs and repair PCs infected with worms. The solution provides the protected network environment without an Agent software installed on the client PCs.

Virus Protected Network

Infected personal computers are blocked from connecting to the corporate LAN; this also prevents the network virus from external network. Detection and removal of network virus, prevention of network mass infection from worms. Repairs virus infected personal computers and provide web interface to manage the network ant-virus appliances and configure security policies.

Total word count: 1,263

References from:

SHATEC Introduction to Information Technology Textbook