Virus Info

A computer virus is a malicious computer program installed on the computer without permission of the user. These programs can be designed to display advertisements or at worst to destroy data and programs while spreading to other computers. Anti-virus programs are utilities that remove computer viruses. Unlike adware/spyware, viruses must have two criteria:(1) it must execute itself, i.e. start itself and (2) it must replicate itself. The only way to remove these viruses is through a virus removal.

The damage varies from virus to virus and infects individual workstations and network servers. Some virus programs will infect programs and destroy them or prevent programs from operating, some may reformat the hard drive, some delete files and some viruses will destroy the boot sector preventing the computer from booting up or restarting. Some less harmful viruses will replicate themselves and present media on the desktop such as text, video, audio or advertisements that our computer repair has extensively experienced. These malwares use resources generally reserved for other programs and can slow the computer considerably. Some of the viruses are often poorly written with bugs and will cause systems to crash with possible data loss.

Five Types of Viruses

Boot sector viruses

Boot sector viruses reside in the memory and most are written for DOS. The virus attaches itself to the part of the boot sector that has a small program that runs during bootup. When an infected floppy disk is used to attempt to start the machine the virus will continue to reside in memory where it will attach itself to all floppy disks that are not write-protected.

Master boot record viruses

Master boot record viruses are similar to boot sector viruses, residing in the memory and usually written for DOS, however, the difference is where the virus code is written. The virus generally moves the intact boot record to another location. Windows FAT partitions can boot to DOS and run an antivirus prgram while NTFS partitioned computers will need to restore the system using the three Windows NT Setup disks.

File infector viruses

File infector viruses invade program/executable files and after the memory is infected it will attach itself to any executable program that is started. These virus types can be spread by running a floppy disk, spread by a hard drive or by a computer network.

Multi-partite viruses

Multi-partite viruses, also known as polypartite viruses, infect the boot records and program files simultaneously. To get rid of the virus both the boot record and program files must be clean of the virus. If the virus is removed only from the program files but not the boot record the files will become reinfected and the reverse is the same, if the virus is not cleaned from the program files but only from the boot record, the virus will reinfect the boot record. These type viruses can be more difficult to clean.

Macro viruses

Macro viruses infect data files, were the most common malware obstructions and have cost corporations a huge amount of undisclosed money and time. All of these viruses use another applications programming language. Usually written with Visual Basic it infects a variety of data from different programs such as Microsoft Word, Excel, Access, PowerPoint and with newer macro virus versions infecting many other programs. There were thousands of macro virus variants in circulation at one time that contributed to substantial data recovery.

A "Proof of Concept Virus" is a "concept of a virus" written by a malicious programmer to show off their skill by exploiting particular vulnerabilities in specific software and operating systems. The effort is a test phase to see if it could actually happen "in the wild".

Trojans are programs that get their name from the Greek fable where a large wooden horse on wheels was delivered to Troy as a gift. After the horse was wheeled into the guarded fortress, Greek soldiers hidden within the horse emerged and captured the city. These programs are downloaded through pictures or programs that appear to be helpful or entertaining but contain programs designed to capture your information or keystrokes on your computer.

The first stage of the trojan is to place itself on the host computer and the next stage it usually downloads other programs from the internet. Those programs may capture your keystrokes from bank accounts, passwords to online banking, credit cards, etc. Some of the programs may also install spyware/adware that brings popups to host computers. Other misdeeds of trojan horses include Denial of Service (DOS) attacks where the host computer sends out signals known as pings in order to make servers, i.e. websites, unavailable.