"Malware" is short for malicious software and used as a single term to refer to virus, spy ware, worm etc. Malware is designed to cause damage to a stand alone computer or a networked pc. So wherever a malware term is used it means a program which is designed to damage your computer it may be a virus, worm or Trojan.
Worms are malicious programs that make copies of themselves again and again on the local drive, network shares, etc. The only purpose of the worm is to reproduce itself again and again. It doesn’t harm any data/file on the computer. Unlike a virus, it does not need to attach itself to an existing program. Worms spread by exploiting vulnerabilities in operating systems
Examples of worm are: - W32.SillyFDC.BBY
Due to its replication nature it takes a lot of space in the hard drive and consumes more cpu uses which in turn makes the pc too slow also consumes more network bandwidth.
Virus is a program written to enter to your computer and damage/alter your files/data. A virus might corrupt or delete data on your computer. Viruses can also replicate themselves. A computer Virus is more dangerous than a computer worm as it makes changes or deletes your files while worms only replicates itself with out making changes to your files/data.
Examples of virus are: - W32.Sfc!mod
Viruses can enter to your computer as an attachment of images, greeting, or audio / video files. Viruses also enters through explainer video
downloads on the Internet. They can be hidden in a free/trial softwares or other files that you download.
So before you download anything from internet be sure about it first. Almost all viruses are attached to an executable file, which means the virus may exist on your computer but it actually cannot infect your computer unless you run or open the malicious program. It is important to note that a virus cannot be spread without a human action, such as running an infected program to keep it going.
Virus is of different types which are as follows.
1) File viruses
2) Macro viruses
3) Master boot record viruses
4) Boot sector viruses
5) Multipartite viruses
6) Polymorphic viruses
7) Stealth viruses
File Virus:-This type of virus normally infects program files such as .exe, .com, .bat. Once this virus stays in memory it tries to infect all programs that load on to memory.
Macro Virus: - These type of virus infects word, excel, PowerPoint, access and other data files. Once infected repairing of these files is very much difficult.
Master boot record files: - MBR viruses are memory-resident viruses and copy itself to the first sector of a storage device which is used for partition tables or OS loading programs .A MBR virus will infect this particular area of Storage device instead of normal files. The easiest way to remove a MBR virus is to clean the MBR area,
Boot sector virus: - Boot sector virus infects the boot sector of a HDD or FDD. These are also memory resident in nature. As soon as the computer starts it gets infected from the boot sector.
Cleaning this type of virus is very difficult.
Multipartite virus: - A hybrid of Boot and Program/file viruses. They infect program files and when the infected program is executed, these viruses infect the boot record. When you boot the computer next time the virus from the boot record loads in memory and then start infecting other program files on disk
Polymorphic viruses: - A virus that can encrypt its code in different ways so that it appears differently in each infection. These viruses are more difficult to detect.