How can I tell if my computer has a virus? Windows 7 If you can answer "yes" to any of the following questions, your computer might have a virus. Is your computer running very slowly? A common symptom of a virus is much slower than normal computer performance. However, there can be other reasons for slow performance, including a hard disk that needs defragmenting, a computer that needs more memory (RAM), or the existence of spyware or adware. For more information about spyware, see How to tell if your computer is infected with spyware. Are you getting unexpected messages, or are programs starting automatically? Some viruses can cause damage to Windows or some of your programs. The results of this damage might include messages appearing unexpectedly, programs starting or closing automatically, or Windows shutting down suddenly. Is your modem or hard disk working overtime? An e-mail virus works by sending many copies of itself by e-mail. One indicator of this is that the activity light on your broadband or external modem is constantly lit; another is the sound of your computer's hard disk continually working. These are not always symptoms of a computer virus, but when combined with other problems, can indicate a virus infection. To check for viruses, scan your computer with an antivirus program. New viruses appear every day, so keeping your antivirus program updated is important. For more information about computer security, go to the Security at Home page on the Microsoft website. To learn how to remove malicious software (malware) from your computer, go to the Microsoft Safety Scanner webpage. How do I find and remove a virus? Applies to Windows 8.1 A fast way to check whether your PC has a virus is to use Windows Defender. This malware protection is included with Windows and helps identify and remove viruses, spyware, and other malicious software. Notes If you're using Windows 8.1, you can run a scanner or antimalware app provided by another company if you prefer. To keep your PC running smoothly, you should only install and run one antimalware app at a time. If you're using Windows RT 8.1, Windows Defender is always on and can't be turned off. To scan your PC with Windows Defender 1. Open Windows Defender by swiping in from the right edge of the screen, and then tapping Search (or if you're using a mouse, pointing to the upper-right corner of the screen, moving the mouse pointer down, and then clicking Search), entering defender in the search box, and then tapping or clicking Windows Defender. 2. Under Scan options, pick the type of scan you want to run: A Quick scan checks only the areas on your PC that malicious software is most likely to infect, and any apps currently running. A Full scan checks all the files on your PC. Depending on your PC, this scan might take an hour or more. A Custom scan checks only the files and locations that you choose. 3. Tap or click Scan now. Remove a virus manually Windows Defender will typically remove viruses automatically. However, in some cases you might need to remove a virus manually. This can be a technical process that you should try only if you've exhausted all other options, you're familiar with the Windows registry, and you know how to view and delete system and program files in Windows. First, run your antimalware app to identify the virus by name. If you don't have an antimalware app or if your app doesn't detect the virus, you might still be able to identify it by looking for clues about how it behaves. Write down the words in any messages it displays, or, if you received the virus in email, write down the subject line or name of the file attached to the message. Then search an antivirus provider's website or the Microsoft Malware Protection Center for references to what you wrote down or to try and find the name of the virus and instructions for how to remove it. For recovery and prevention After the virus is removed, you might need to reinstall some software or restore lost info. Making regular backups of your files can help you avoid data loss if your PC gets infected again. If you haven't made backups in the past, it's a good idea to start now. For more info, see Restore files or folders using File History. For additional tips on how you can help protect your PC from viruses, see How can I help protect my PC from viruses? How To Properly Scan Your Computer for Viruses, Trojans, and Other Malware Completely and correctly scanning your computer for malware like viruses, Trojan horses, rootkits, spyware, adware, worms, etc. is often a very important troubleshooting step. A simple virus scan will no longer do. Many forms of malware cause or masquerade as seemingly unrelated PC issues like Blue Screens of Death, issues with DLL files, and other serious Windows problems so it's important to properly check your computer for malware when working to solve many problems. Note: These are general steps to scan and remove malware from your PC and should apply to any Windows operating system. Difficulty: Easy Time Required: Properly scanning your PC for viruses and other malware could take several minutes or longer Applies To: Scanning your computer for malware this way works similarly with Windows 8 (includingWindows 8.1), Windows 7, Windows Vista, andWindows XP. Here's How: 1. Download and run the Microsoft Windows Malicious Software Removal Tool. This free, Microsoft provided malware removal tool won't find everything, but it will check for "specific, prevalent malicious software" which is a good start. Here's a list of everything it will find and remove. Note: You may already have the Malicious Software Removal Tool installed. If so, make sure you update it using Windows Update so it can scan for the latest malware. 2. Update your anti-virus/anti-malware software installed on your computer. Before running a virus scan or malware scan, you need to make sure the virus definitions are up to date. These regular updates tell your anti-virus software how to find and remove the latest viruses from your PC. Important: Don't have a virus scan program installed? Download one now! There areseveral free anti-virus programs available so there's no excuse for not running one. 3. Run a complete virus scan on your entire computer. If you have a dedicated malware scanner that does more than look for viruses, run a full scan using that program too. Note: Don't simply run the default system scan which may not include many important parts of your PC. Check that you're scanning every part of every single hard drive and other connected storage device on your computer. Important: Make sure any virus scan includes themaster boot record, boot sector, and any applications currently running in memory. These are particularly sensitive areas of your computer that can harbor the most dangerous malware. Tips: 1. If you've scanned your entire computer for viruses but suspect that it may still be infected, try a free on- demand virus scanner next. An online virus scan is yet a further step you can take, at least in situations where you have a good idea what file(s) may be infected. Antivirus software From Wikipedia, the free encyclopedia "Antivirus" redirects here. For the antiviral medication, see Antiviral drug. An example of free antivirus software: ClamTk. Antivirus, anti-virus, or AV software is computer software used to prevent, detect and remove malicious computer viruses. Most software described as antivirus also works against other types of malware, such as malicious Browser Helper Objects(BHOs), browser hijackers, ransomware, keyloggers, backdoors, rootkits, trojan horses, worms, malicious LSPs, dialers,fraudtools, adware and spyware.[1] Computer security, including protection from social engineering techniques, is commonly offered in products and services of antivirus software companies.[2] This page discusses the software used for the prevention, detection, and removal of malware threats, rather than computer security implemented by software methods. A variety of strategies are typically employed. Signature-based detection involves searching for known patterns of data withinexecutable code. However, it is possible for a computer to be infected with new malware for which no signature is yet known; and malware is often modified to change its signature without affecting functionality. To counter such so-called zero-day threats, heuristics can be used. One type of heuristic approach, generic signatures, can identify variants by looking for slight variations of known malicious code in files. Some antivirus software can also predict what a file will do by running it in asandbox and analyzing what it does to see if it performs any actions which could be malicious. Antivirus software has some drawbacks. It can impair a computer's performance.[3] Inexperienced users can be lulled into a false sense of security when using the computer, considering themselves to be totally protected, and may have problems understanding the prompts and decisions that antivirus software presents them with. An incorrect decision may lead to a security breach. If the antivirus software employs heuristic detection, it must be fine-tuned to minimize misidentifying harmless software as malicious (false positive).[4] Antivirus software itself usually runs at the highly trusted kernel level of the operating system to allow it access to all the potential malicious process and files, creating a potential avenue of attack.[5] Contents [hide] 1 History 2 Identification method o 2.1 Signature-based detection o 2.2 Heuristics o 2.3