Malicious software program loaded into a users computer without the users knowledge and

This page provides an overview of the most common malware applications. For specific steps you can take to protect against malware, see our Protect Against Viruses & Security Threats pages.

What is Malware?

Malware is a catch-all term for various malicious software, including viruses, adware, spyware, browser hijacking software, and fake security software.

Once installed on your computer, these programs can seriously affect your privacy and your computer's security. For example, malware is known for relaying personal information to advertisers and other third parties without user consent. Some programs are also known for containing worms and viruses that cause a great deal of computer damage.

Types of Malware

• Viruses which are the most commonly-known form of malware and potentially the most destructive. They can do anything from erasing the data on your computer to hijacking your computer to attack other systems, send spam, or host and share illegal content.
• Spyware collects your personal information and passes it on to interested third parties without your knowledge or consent. Spyware is also known for installing Trojan viruses.
• Adware displays pop-up advertisements when you are online.
• Fake security software poses as legitimate software to trick you into opening your system to further infection, providing personal information, or paying for unnecessary or even damaging "clean ups".
• Browser hijacking software changes your browser settings (such as your home page and toolbars), displays pop-up ads and creates new desktop shortcuts. It can also relay your personal preferences to interested third parties.

Facts about Malware

Malware is often bundled with other software and may be installed without your knowledge.
For instance, AOL Instant Messenger comes with WildTangent, a documented malware program. Some peer-to-peer (P2P) applications, such as KaZaA, Gnutella, and LimeWire also bundle spyware and adware. While End User License Agreements (EULA) usually include information about additional programs, some malware is automatically installed, without notification or user consent.

Malware is very difficult to remove.
Malware programs can seldom be uninstalled by conventional means. In addition, they ‘hide’ in unexpected places on your computer (e.g., hidden folders or system files), making their removal complicated and time-consuming. In some cases, you may have to reinstall your operating system to get rid of the infection completely.

Malware threatens your privacy.
Malware programs are known for gathering personal information and relaying it to advertisers and other third parties. The information most typically collected includes your browsing and shopping habits, your computer's IP address, or your identification information.

Malware threatens your computer’s security.
Some types of malware contain files commonly identified as Trojan viruses. Others leave your computer vulnerable to viruses. Regardless of type, malware is notorious for being at the root, whether directly or indirectly, of virus infection, causing conflicts with legitimate software and compromising the security of any operating system, Windows or Macintosh.

How do I know if I have Malware on my computer?

Common symptoms include:

Browser crashes & instabilities

• Browser closes unexpectedly or stops responding.
• The home page changes to a different website and cannot be reset.
• New toolbars are added to the browser.
• Clicking a link does not work or you are redirected to an unrelated website.

Poor system performance

• Internet connection stops unexpectedly.
• Computer stops responding or takes longer to start.
• Applications do not open or are blocked from downloading updates (especially security programs).
• New icons are added to desktop or suspicious programs are installed.
• Certain system settings or configuration options become unavailable.

Advertising

• Ads pop up even when the browser is not open.
• Browser opens automatically to display ads.
• New pages open in browser to display ads.
• Search results pages display only ads.

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.

Stealth viruses: These types of viruses use different kind of techniques to avoid detection. They either redirect the disk head to read another sector instead of the one in which they reside or they may alter the reading of the infected file’s size shown in the directory listing. For example, the Whale virus adds 9216 bytes to an infected file; then the virus subtracts the same number of bytes (9216) from the size given in the directory.

Which malicious software is loaded in the computing system without user's knowledge?

What is malicious software called?

Which type of malware is a program or piece of code that is loaded onto a person's computer without his knowledge and runs against his wishes?

What is the name of a software which prevents malicious software from entering a computer?