Tag: DOS

Sometime the term computer virus is used to describe a logic bomb in which a piece of unauthorized code acts as a parasite that attaches it self to a host program during a copy operation. Like their biological counterparts computer viruses reproduced and spread; copy commands embedded in the virus code to make, it reproduce and transmit commands may be inserted to spread the virus from one computer to the other on its network. Unfortunately, viruses are common in today’s, computer system and the potential problems they may cause must be addressed. In 1992, the potential problems became even worse. Professional computer viruses fighters were outraged by the publication of the book that contain the source code heeded to create potentially destructive viruses, plus coupons for floppy disk containing executable virus program.

To be able to analyze and remove viruses from the computer system you need to ascertain its type some of the types have been discussed below:

Macro Viruses

Developing Viruses

Boot Sector Viruses

Macro Viruses:

Macro virus is the first virus to infect the data files, rather than executable. Macro viruses infects the files in the form of macro or OLE objects and are easier to write than “traditional” files viruses which are mostly written in assembly code. Today many applications have macro languages, so the problem is a growing one. Macro viruses spread by people sending infected files to each other, entirely innocently, either on floppy disk, or via the internet LAN, or via an external e-mail system.

Many applications provide the functionality to create macros. A macro is a series of commands to perform some application specific task. Macros are designed to make, life easier like automating some everyday tasks, for instance, doing calculations. Macros can be saved as a series of keystrokes; or they can be written in some macros languages.

Developing Viruses:

Some viruses are badly written and “lose” their own macros. The original virus may consist of the set (Auto Open, File Save, and File Save As), if the replicates via Auto Open, the complete macro set will be preserved. However, if the user invokes File (Save As), the virus will fail to copy the File Save macro. The resulting virus set (Auto Open, File. Save As) is known as developed Macro and original virus is developing.

Boot Sector Viruses:

Once of the most common kind of viruses are boot sector viruses, for example. Form and Stoned. These viruses infected the floppy disks in either of the following parts:

Master Boot Record (MBR)

Partition Sector of the DOS Boot Record (DBR)

DOS Boot sector of hard disks

The following examples shows how a boot sector virus spreads: you have got a floppy disk with data on it, perhaps some page maker file. This is part of a project that you are doing jointly with a classmate. What your classmate does not know is that his computer is infected with a boot sector virus and therefore, so is the disk that has been sent to you. You put the disk in drive A: and start using these files. So far, the virus has not done anything. But when you finish for the day, you switch off the computer and go home. The next day, you come and switch on. The floppy disk is still in drive A. so the computer is trying to boot up from there. It loads the first sector into memory and executes it, or if it cannot find DOS on the disk, tells you: “Not a system disk, please press any key to continue”. Everyone has seen this message numerous times.

Computer occupies an important place in many of the industries and they employ computer skilled personnel to carry out their jobs efficiently and effectively. This trend is found not only in companies but also in growing banking sector. The banks which provide a plenty of customer services like corporate banking, financial assistance, savings, and investment, find it easier to computerize these services. Internet banking is considered as a boon for all busy people, which makes it easy to transfer and receive money quickly. It also gives the exact information of the amount in the bank accounts.

Importance of computer knowledge in banks:

As the computers are dominating the industrial world completely, it is quite natural that banks also insist their employees must have basic knowledge in computer. This makes the fresher easily understand their jobs which are performed on the computer. Computer knowledge makes it easy for the fresher to get training for probationary officer posts and for clerical posts. In other words, the candidates can go for a computer course in a reputed institute for 6 months to gain more knowledge in computer and improve their chances of being hired in banks. Many banks have started to set this eligibility criterion to stress this point. Still some candidates may question whether computer skill is mandatory to join in banks. The answer is it is necessary as most of the banks are fully computerized and they have adopted the core banking.

Most of the private and public sector banks find the usage of computer is so essential to network between their branches and to provide faster and effective service. Hence, as most of the banks are moving towards the core banking, it is necessary that the candidates who are applying for banking jobs must have knowledge in DOS, internet, e-mail and MSOffice. It is very true that a clerk should know all the basics about using computer. This is compulsory in many cases and it is advantage for others. A probationary officer in banks must know about MSWord, MS Excel, Window operating system and they should have a sound knowledge in MS Access. Certifications in these courses are insisted in many cases. This quality proves to be essential to handle files, documents and records maintained in computer in different branches and banks effectively.

Computers have incredible capabilities. They can accomplish great tasks, communicate clearly, make things move and think beyond human measure. Computers have become like humans in nearly every conceivable manner, so it’s no surprise that computers can also get sick.

The computer revolution first began picking up speed in the late 1980s. Since then, it has evolved to be a vital element in our society, our corporate and our personal lives. Computers have become part and parcel to virtually everything we do day in, and day out. But with all good comes a little bad. Some users have maliciously created computer viruses that have grave effects. The range of computer viruses existing in our modern networks has a huge prominence in our lives, because of all the ways we depend on computers. Despite our need for dependable computers, some people have nothing better to do but exercise their computer knowledge in a destructive way, creating computer viruses.

The first computer virus, called “The Brain”, was created in 1986. The Brain is a boot-sector virus, which occupies unused space on the disk to eliminate further use of memory space. After it was created, The Brain quickly spread worldwide in 1987. The Brain virus was considered first to use stealth techniques, making the virus difficult to detect.

On November 1, 1987 another virus appeared. The Lehigh virus was named after Lehigh University, the place where this particular virus was first discovered. One Friday the thirteenth, in December of that same year, the Jerusalem virus was discovered at Hebrew University. This virus has also gone by the names “ArabStar”, “Friday the 13th” and the “Black Window”. This is one of the oldest and best-known computer viruses in the world.

Two more viruses surfaced in 1988: the Stone, which was the first bootstrap virus, and the Internet Worm. The Internet Worm caused mayhem in the corporate world as it crossed the United States overnight through a series of computer networks. Then in 1989, the Dark Avenger was introduced. This was a fast-infector that possessed the capability to infect new files despite the presence of anti-virus software. The Dark Avenger computer virus was designed to damage a system slowly. The virus would go unnoticed at first, and damaged files would not be backed up. Slowly it would consume more and more of your computer until it had created permanent damage.

Computer manufacturers and software engineers began the public war against computer viruses around 1990. Corporations began to respond to growing public concern and the number of anti-virus products began to rise. The threat of computer viruses was finally taken seriously. McAfee, IBM, Digital Dispatch and Iris all introduced their anti-virus products and software in 1990. Despite their efforts, computer viruses grew faster, stronger and sneakier. Symantec Norton anti-virus was introduced was introduced in 1991.

The introduction of Windows 95 brought both relief and discomfort to anti-virus companies when it was released in 1995. At that time, most common computer viruses were still boot viruses that worked on DOS, but couldn’t replicate on Windows 95. Then micro viruses were discovered in late 1995. These computer viruses performed in the MS-Word environment, rather than DOS. Again, the anti-virus industry faced challenges to fight against these new batches of viruses. With the introduction and growing popularity of the Internet in the late 1990s, viruses began to spread at a much faster rate.

Throughout 1998 there was no lessening of computer virus attacks MS Office, MS Windows, MS Office and network applications. New viruses continued to appear, and computers and advanced network-to-do applications continued to be affected. In 1999, another virus appeared, infecting computers using Microsoft Word. This computer virus may have been passed on via MS Outlook, or through Outlook Express e-mail programs.

The “Loveletter” virus, also known as “Love Bug” and the “I Love You” virus, is believed to have struck one in five PCs worldwide, making it the most widespread and the most costly computer virus the world had ever seen. The “I Love You Virus” created panic and discord around the globe. The virus was transferred by e-mail. When the receiver opened the attachment, the virus was automatically sent to everyone in the user’s address book. The “I Love You” computer virus spread at a dizzying rate of speed.

As long as we continue to use the Internet and share computer files, we are at risk of catching computer viruses. Even today, more and more viruses are still being discovered, leading to big problems for all users, and creating ongoing dilemmas for the creators of anti-virus programs.

Like people, getting sick is an unfortunate fact of life for computers. Using up-to-date anti-virus software is a sort of preventative medicine, helping to keep computers healthy and computer viruses at bay.