A worm is computer code that spreads without user interaction. Most worms begin as email attachments that infect a computer when they're opened. The worm scans the infected computer for files, such as address books or temporary webpages, that contain email addresses. The worm uses the addresses to send infected email messages, and frequently mimics or spoofs the "From" addresses in later email messages so that those infected messages seem to be from someone you know.
Worms then spread automatically through email messages, networks, or operating system vulnerabilities, frequently overwhelming those systems before the cause is known. Worms aren't always destructive to computers, but they usually cause computer and network performance and stability problems.
A trojan horse is a malicious software program that hides inside other programs. It enters a computer hidden inside a legitimate program, such as a screen saver. Then it puts code into the operating system that enables a hacker to access the infected computer. Trojan horses do not usually spread by themselves. They are spread by viruses, worms, or downloaded software. Spyware can install on your computer without your knowledge.
Spyware can track Internet search habits and can also redirect your web browser to a different website than you intend to go to. A rogue security software program tries to make you think that your computer is infected by a virus and usually prompts you to download or buy a product that removes the virus. The names of these products frequently contain words like Antivirus, Shield, Security, Protection, or Fixer.
This makes them sound legitimate. They frequently run right after you download them, or the next time that your computer starts.
Rogue security software can prevent applications, such as Internet Explorer, from opening. Rogue security software might also display legitimate and important Windows files as infections. Typical error messages or pop-up messages might contain the following phrases:. Do not click anything inside the dialog box. Are you sure you want to navigate from this page? Your computer is infected! They can cause data lost and file corruption and need to be treated as soon as possible. Return to System Security and download it to secure your PC.
Press OK to Continue or Cancel to stay on the current page. For more information see Protect yourself from tech support scams. Removing a computer virus or spyware can be difficult without the help of malicious software removal tools. Some computer viruses and other unwanted software reinstall themselves after the viruses and spyware are detected and removed. Fortunately, by updating the computer and by using malicious software removal tools, you can help permanently remove unwanted software.
For more information about how to remove a computer virus and spyware, see the following article in the Microsoft Knowledge Base: - Microsoft resources and guidance for removal of malware and viruses.
Note A computer virus may prevent you from accessing the Microsoft Update website to install the latest updates. We recommend that you set the Automatic Updates service to run automatically so that a computer is not missing any important updates. Microsoft offers a free online tool that scans and helps remove potential threats from your computer. To perform the scan, go to the Microsoft Safety Scanner website.
Note the name of the rogue security software. For this example, we'll call it XP Security Agent When you are prompted, use the arrow keys to highlight Safe Mode with Networking , and then press Enter.
Follow tips and techniques for washing hands. Follow tips for Coughing and sneezing without contaminating. Avoid touching your nose, eyes and mouth with unwashed hands.
The nose, eyes and mouth are entry sites for viruses and bacteria. Avoid touching your nose, eyes and mouth. These are entry points for viruses and bacteria. Avoid contact with people that are sick as they may be contagious. Do not get close to them and do not touch objects they have used, like their utensils for instance. Clean your surroundings regularly, as well as the sanitary appliances you use.
For example, clean your counters and other surfaces that you touch often with your hands. Also wash toilets and sinks in order to keep them clean. Cleaning is very effective in killing viruses, which can survive on hard surfaces. Clean with soap and water or use domestic detergents. They live in grassy and brushy areas and are most prevalent during wet seasons.
A common hiding place is in wet leaves. They often infest animals, including field mice and deer. And they may be transported into your home by your pets. Controlling the population of mice or rats in and near your home can help you avoid pathogens spread by rodents and also help control the population of ticks that spread disease. Rodents can harbor a number of pathogens, including lymphocytic choriomeningitis virus, leptospirosis, plague, and hantavirus. Other wild animals can also transmit rabies and other infections.
The following measures can help you avoid getting sick from diseases transmitted by animals:. As a service to our readers, Harvard Health Publishing provides access to our library of archived content.
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