Computer virus information
What is a virus?
A virus is a piece of software designed and written to adversely affect your computer by altering the way it works without your knowledge or permission. In more technical terms, a virus is a segment of program code that implants itself to one of your executable files and spreads systematically from one file to another. Computer viruses do not spontaneously generate: They must be written and have a specific purpose. Usually a virus has two distinct functions:
Spreads itself from one file to another without your input or knowledge. Technically, this is known as self-replication and propagation.
Implements the symptom or damage planned by the perpetrator. This could include erasing a disk, corrupting your programs or just creating havoc on your computer. Technically, this is known as the virus payload which can be benign or malignant at the whim of the virus creator.
A benign virus is one that is designed to do no real damage to your computer. For example, a virus that conceals itself until some predetermined date or time and then does nothing more than display some sort of message is considered benign.
A malignant virus is one that attempts to inflict malicious damage to your computer, although the damage may not be intentional. There are a significant number of viruses that cause damage due to poor programming and outright bugs in the viral code. A malicious virus might alter one or more of your programs so that it does not work as it should. The infected program might terminate abnormally, write incorrect information into your documents. Or, the virus might alter the directory information on one of your system area. This might prevent the partition from mounting, or you might not be able to launch one or more programs, or programs might not be able to locate the documents you want to open.
Some of the viruses identified are benign; however, a high percentage of them are very malignant. Some of the more malignant viruses will erase your entire hard disk, or delete files.
WHAT VIRUSES MAY DO
The following are possibilities you may experience when you are infected with a virus. Remember that you also may be experiencing any of the following issues and not have a virus.
Once the hard drive is infected any disk that is non-write protected disk that is accessed can be infected.
Various messages in files or on programs.
Changes volume label.
Marks clusters as bad in the FAT.
Randomly overwrites sectors on the hard disk.
Replaces the MBR with own code.
Create more then one partitions.
Attempts to access the hard disk drive can result in error messages such as invalid drive specification.
Causes cross linked files.
Causes a "sector not found" error.
Cause the system to run slow.
Logical partitions created, partitions decrease in size.
A directory may be displayed as garbage.
Directory order may be modified so files such as COM files will start at the beginning of the directory.
Cause Hardware problems such as keyboard keys not working, printer issues, modem issues etc.
Disable ports such as LPT or COM ports
Caused keyboard keys to be remapped
Alter the system time / date
Cause system to hang or freeze randomly.
Cause activity on HDD or FDD randomly.
Increase file size.
Increase or decrease memory size.
Randomly change file or memory size.
Extended boot times
Increase disk access times
Cause computer to make strange noises, make music, clicking noises or beeps.
Different types of error messages