A virus may enter a system through a downloaded e-mail, advertisement, cookie, spam mail or an infected website. Apart from this, a virus may come in through portable devices like floppy, CD, DVD or USB drive. Once it is inside, the virus starts replicating itself rapidly, taking up space and corrupting or wiping other files. Like its biological counterpart, once the virus has spread through the ‘vital organs’ of the computer’s ‘body’, the programme files are attacked, the whole system crashes. Just like a doctor first diagnoses a problem and then eradicates it, an anti-virus is a programme that detects and kills viruses. Various aspects of computer virus have been discussed below:
Kinds of VirusesViruses are being invented every day, and so are anti-viruses. It is difficult to keep pace with those who write malware programmes since they are usually very intelligent and resourceful people. However, the main categories of viruses, as given below, are more or less comprehensive, since most viruses fall into one of these sectors.
Macro Virus: The beauty of the Macro is that it is written in the language of the applications. As a result, it does not have to depend on any particular platform, and spreads all over the operating system. Melissa A. is an example of this kind of ‘high alert’ viruses.
Network Virus: A network virus spreads through shared files and folders over a LAN (Local Area Network) connection. When a network virus reaches a computer, it quickly searches through the network and locates its next destination. In this manner, it moves through the entire LAN, infecting it, crashing the server and deleting data, as its cycle keeps repeating.
Logic Bombs: This virus is actually a code that gets activated when a certain function happens. Its creators like to set it up on April Fools Day, New Year’s Eve and other such occasions. When the victim clicks on a certain button on a site, or opens an attached file, the ‘bomb’ is blown, and the activated virus starts deleting files permanently by its rapid activity.
Companion Virus: This is more or less extinct by now since it had been made with MS-DOS in mind. The virus creates a new .COM or .EXE file inside the system. When the user keys in the name of a programme without adding the required extension, the system assumes that the file that comes alphabetically first in order should be offered, and this is the companion virus file. With the advent of the Windows version of Microsoft, companion viruses cannot gain control of the file systems so easily any more.
Boot Sector Virus: Another semi-extinct virus, it had its heyday when floppies were more common and CDs were still too costly. This virus hides itself in the bootable disk itself, and aims at damaging the hard drive rather than attacking the files. It was quite potent since it damaged the drive when it was booted, and usually managed to push things beyond recovery.
Multiple Virus: This one is far from obsolete and is CD/DVD, USB drive-compatible. Like its predecessor, the multiple virus spreads through infected media devices and hides in its memory. It journeys from the boot sector to the .exe files on the hard drive, and then affects the entire system corrupting the files which are gradually deleted.
Recovering from Data Loss Now that we know how quickly, efficiently and thoroughly a virus can damage our carefully stored data, something needs to be said about how to recover from a data loss scenario generated by a virus attack. Firstly, we should always have a good antivirus software and firewall installed. The antivirus must be updated regularly if we are to avoid an unpleasant surprise. We should also avoid opening unsolicited mails with strange attachments. A spam guard or mail filtering system can be activated. Downloading music, movie clips and free software from tempting internet sites is the best way to invite a virus that can delete all your important data by overwriting them. It is always more profitable to stick to original paid versions of software; a few pounds on this would save you thousands of pounds worth data.
Finally, if the situation seems to be really serious, one should either go for a verified data recovery software from a reputed company, or just hand the disk over to a data recovery company if it concerns massive volumes of important data.
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