How Virus Remove Without Antivirus

how virus enter into computer and how virus replicate within host cell and how virus spread in computer and how remove virus from computer
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Prof.SteveBarros,United Kingdom,Teacher
Published Date:28-07-2017
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04_574183 pt01.qxd 7/23/04 10:05 AM Page 9 Part I Evaluating Your Virus Situation04_574183 pt01.qxd 7/23/04 10:05 AM Page 10 In this part . . . any factors contribute to the likelihood that your Mcomputer will get infected with a virus. Your han- dling of e-mail messages from people you don’t know is one of the biggest factors, as is the general health of your antivirus software. Does your computer have a virus — right now? Wouldn’t you like to know? Some symptoms may indicate a virus, but other symptoms probably don’t. By performing a simple procedure, you can determine this reliably. If you have a virus, a couple more steps and ZAP, it’s gone. And with relative ease, you can eliminate any spyware on your computer, too. Many computing habits are associated with a far lower risk of getting infected by computer viruses and other similar trouble. Among them are keeping your antivirus software up to date and periodically installing security patches. The first important task to virus-free computing is to check whether your computer has antivirus software, and if so, whether it’s in good condition or not. There are a number of ways to tell whether antivirus software is present, and whether its basic components are functioning correctly.05_574183 ch01.qxd 7/23/04 10:05 AM Page 11 Chapter 1 Understanding Virus Risks In This Chapter  Figuring out whether you’re at risk  Making good security decisions here’s an old saying: “Just because you’re not paranoid Tdoesn’t mean that everyone isn’t out to get you.” This saying is proven by the people who write computer viruses — they are out to get you And, in fact, a little paranoia may go a long way in protecting your computer. In this chapter, I provide you with the factors that may increase your personal level of useful paranoia — in other words, the factors that can influence you to lower your per- sonal risk level. Why? Because, get this, some people are more apt to catch computer viruses than others, and it’s largely based upon some basic factors such as the version of Windows they’re using, as well as their Internet and e-mail habits. In the computer world as well as in the biological world, good hygiene goes a long way in preventing infection in the first place — and prevention is far easier to deal with than curing an infection after it happens.05_574183 ch01.qxd 7/23/04 10:05 AM Page 12 Part I: Evaluating Your Virus Situation 12 Assessing the Threat to Your Computer Three primary factors contribute to your risk of catching viruses:  The version of the Windows operating system you are using  Whether you have installed security patches on your computer  How many people use the computer But also important are your Internet browsing habits:  Do you visit many different Web sites?  Do you visit sites that try to mess with your computer’s settings (and how would you know — and prevent — that)?  Do you have a tendency to open e-mail attachments from people you don’t know?  Do you visit Web sites cited in e-mail messages from strangers? All these factors have a direct bearing on whether you are prone to catching viruses. Finally, the manner in which your computer is connected to the Internet determines your susceptibility to viruses. If you have a high-speed, “always-on” Internet connection, then virus writers are actively trying to find you (or already have). Dial- up connections are somewhat less risky — but not risk-free. Which operating system are you using? Microsoft’s earlier versions of Windows had very little in the way of security — they conformed to Microsoft’s earlier (and flawed) premise that everyone in corporations and everyone05_574183 ch01.qxd 7/23/04 10:05 AM Page 13 Chapter 1: Understanding Virus Risks 13 on the Internet is nice and can be trusted and that no one will do anything bad. Microsoft, by the way, has been humbled by the experience and, as a result, the newer versions of Windows are far more secure than their predecessors. Windows 95 and Windows 98 Collectively known as Windows 9x, these earlier versions of Windows lack the basic security components found in modern operating systems. Their primary fault is that they don’t sepa- rate the function of the operating system from the person who uses it. You, the computer’s user, have complete control over every aspect of the computer. Even back in the ’90s that wasn’t too safe; if you catch a virus, the virus has the same range of control over your computer as you do. Microsoft no longer supports Windows 95. This means that, if any security vulnerability is discovered in Windows 95, Microsoft will not issue bulletins, advice, or security patches to fix it. Not an enviable position for any user to be in. In 2003, Microsoft announced that it would soon end support for Windows 98. But when thousands of corporate and individ- ual computer users stormed the Microsoft castle in Redmond, Washington, armed with torches, spears, axes, and old dot- matrix printers, Microsoft relented and postponed the Windows 98 “end of life.” But for users of Windows 98, the message is clear: Your days of support from Microsoft are growing short. Windows ME Officially called Windows Millennium Edition or Windows ME (and playfully referred to in some circles as the Windows Miserable Edition), this is just Windows 98 with some addi- tional features thrown in and some stability improvements. The stability improvements come at the price of higher hard- ware requirements, however, and Windows ME suffers from the same basic security issues as its predecessors, namely that viruses can run roughshod throughout the unprotected operating system. Windows 2000 At long last, Microsoft had taken the kernel (insides) of Windows NT and grafted on the Windows 98 user interface05_574183 ch01.qxd 7/23/04 10:05 AM Page 14 Part I: Evaluating Your Virus Situation 14 (the stuff that you see on-screen when you use it), and after exhausting the world’s supply of duct tape and baling wire, made it work. Windows 2000 is a very decent operating system. It contains most of the security features that corporate customers and consumers had been requesting for a long time. Primary is the notion of “logging on” to the computer. In Windows 2000 and newer versions of Windows, if you can’t log on to the com- puter, you can’t use it. Contrast that to Windows 9x — if you can make the computer run, you can use it and do anything you want to it. Windows XP Windows XP contains many refinements over Windows 2000 and is even more secure. For the most part, Windows XP is an improved version of Windows 2000 and includes additional features and functions. I’ve heard some say that Windows XP is just Windows 2000 with the soft, friendly interface. If you haven’t seen Windows XP, it’s like Windows 2000 with brighter colors and smooth, rounded corners. Do you install security patches? Microsoft regularly releases security patches — fixes to their software — that close security holes that could lead to virus infections. Many of these patches are deemed “critical,” and a good number of them have been exploited by those chip-on- their-shoulder Internet thugs who have nothing better to do than to spread misery to as many people as possible. Microsoft has provided a number of ways that you can use to find out about and install security patches, including Windows Update, Automatic Update, and e-mail notifications of new patches. If you do install the critical patches that Microsoft releases, then you’re in far better shape than if you have no security patches at all. Having no security patches is almost as bad as having no antivirus software: You’re up the creek with a sitting duck.05_574183 ch01.qxd 7/23/04 10:05 AM Page 15 Chapter 1: Understanding Virus Risks 15 I don’t want you to feel bad if you’re among (what I suspect is) the majority of computer users — those who have never installed security patches. Had I chosen a different career path without much chance to get familiar with computers, the thought of installing security patches would seem about as intimidating as working on my home’s electrical wiring or working on a late-model automobile with all its complex wiring and safety systems. But that’s what this book is for: to help get you past the reluctance. How many people use the computer? Are you the only person who uses your computer? Or are sev- eral colleagues, family members, or (gasp) total strangers using your computer, like so many people sharing a germ- infested bathroom water cup? The greater the number of people using a computer, the greater the chances are that something bad will happen. How do I know this? When several people share a complex machine like a PC, the inconsistencies in the ways that the people use the computer, and the accumulation of every user’s bad habits and mistakes, can make the computer’s condition deteriorate over time. How is your computer connected to the Internet? While there are many ways to connect to the Internet, I’m con- cerned with just one factor: Is your computer “always on and connected” through any sort of a broadband (high-speed) con- nection like DSL, a cable modem, ISDN, or satellite? Or do you use a dial-up (phone-line) connection to connect your com- puter to the Internet, get your e-mail, do a little surfing, and then disconnect? It boils down to this: Is your computer always on and always connected to the Internet? If so, then your computer is far more likely to be targeted by Internet worms. Some hackers like to scan for — and find — new always-on computers.05_574183 ch01.qxd 7/23/04 10:05 AM Page 16 Part I: Evaluating Your Virus Situation 16 They’re looking for recruits — to see whether they can add your system to their legion of slave computers. Let me explain this high-speed, always-on thing a little more. If your computer is connected to the Internet using a high-speed connection, then your computer is statistically more likely to be found by a scan than it would be if it were connected, say, only one or two hours per day. Statistically speaking, an always-on computer is ten times more likely to be scanned, because it’s connected ten times as many hours per day. But more than that, if your computer is always on and always con- nected, then hackers would consider your computer more dependable. And because the connection is higher speed than dial-up, they can get more performance out of your computer for their own evil purposes. Do you have a firewall? A firewall, as I explain more fully in Chapter 10, is something that is designed to block the probing scans that are often asso- ciated with viruses, worms, and Trojan horses. Those people who have installed either a software firewall or a hardware fire- wall have far better protection than people who have neither. A software firewall is a program that runs on your computer, invisibly (in the background), much like an antivirus program. The software firewall program carefully watches all communi- cation coming into your computer and leaving your computer. Each network message — or packet — is examined to ascertain its type, origin, and destination. These properties are then compared to a list of rules to determine whether each packet should be allowed to pass through or not. Should the message be allowed to pass, the firewall lets it move along towards its destination. But should the message be blocked, then the fire- wall will not permit it to pass — and it will fail to reach its des- tination, like a postal letter that is intercepted in transit and simply thrown away. A hardware firewall is an electronic appliance that is installed on a network. Its internal function is essentially similar to the software firewall, except that its protection is more central- ized: All the computers on the network are protected by the hardware firewall, so none of the bad traffic on the Internet is permitted to reach any of the computers on the network.05_574183 ch01.qxd 7/23/04 10:05 AM Page 17 Chapter 1: Understanding Virus Risks 17 The legion of zombies Many of the viruses, worms, and practical purposes, be “off the air” Trojan horses that have been for as long as the attack continued. released in recent years have a This is no pipe dream or theoretical single, diabolical purpose — to iden- missive. Such attacks are common- tify and “take over” those so-called place. Major corporations, organiza- always-on and always-connected tions, and governments, such as computers that are typically con- Microsoft, SCO, Yahoo, E-Trade, the nected to the Internet using high- U.S. Whitehouse, and some coun- speed DSL, cable modem, ISDN, or tries’ government or news sites, have satellite connections. been victims of DDoS attacks lasting A recent study estimates that fully hours or days. And unless that cor- one-third of all such computers have poration is both clever and resource- backdoors (programs that allow ful, the corporation’s Web site is hackers to bypass all security) essentially unreachable for all legiti- installed on them and are used for a mate use until the attack ceases. variety of purposes — generally for Home users — even those who are transmitting spam (unwanted junk) IT professionals by day — would e-mail or for participating in massive likely have no reason to suspect that distributed denial of service (DDoS) their home PCs have been taken over. attacks. Generally speaking, hackers have A distributed denial of service (DDoS) designed their backdoors to minimize attack is one where a hacker, after the likelihood of being detected. They enlisting hundreds or thousands of use a measured, limited portion of computers with his backdoor pro- your computer’s resources so you gram, sends a command to “his” can continue to use your computer (your) computer, instructing it (and for whatever you do with it. At the many, many others) to begin flooding same time, however, your computer some particular Web site with as would also be used to relay and many network messages as possible. transmit spam to hundreds or thou- The victim’s Web site would then be sands of other unsuspecting people receiving millions of network mes- (and many of those spam messages sages from hundreds or thousands of may contain their own viruses, computers located all over the world worms, or Trojan horses to enlist and be nearly powerless to stop it even more unsuspecting and poorly- (because of the vast number of protected computers). Your computer sources of the attack). As a result, could be the modern version of the the victim’s Web site would, for all zombies in Night of the Living Dead.05_574183 ch01.qxd 7/23/04 10:05 AM Page 18 Part I: Evaluating Your Virus Situation 18 A firewall is like a security guard at the entrance of an office building. He (or she) scrutinizes each person coming and going. He may want to look at each person’s identification by examining their employee badge or other credential. If the person coming or going is carrying anything, he may ask ques- tions about it. If the person is a guest, the guard may request that the user sign their name into a visitor’s log. The guard has a list of rules that he uses to determine whether each person coming and going will be permitted to pass through. Occasionally he will need to turn someone away, for one reason or another. He will detail each such denial so his boss can later view who was denied access and why. Occasionally, the guard will need to call his boss and ask if a visitor is permitted to pass through (in a firewall software pro- gram, this takes the form of a pop-up window that asks if a par- ticular program should be permitted to communicate or not). High-risk activities The types of activities performed on your PC also contribute to your risk, whether high or low. Each of these activities is related to how social you permit your computer to be. Do you often take it out in public where it can exchange information with other computers? In the analogy between biological viruses and computer viruses, a high degree of socialization (mingling with others) increases risk. The following sections look at some examples. Wireless “Hot Spots” Hoping to attract well-to-do customers, many public establish- ments — such as coffee houses, restaurants, and other busi- nesses — have installed so-called Internet hot spots. These hot spots are Internet connections that a customer can use to connect to the Internet with a laptop computer, provided it’s equipped with a wireless networking (also called Wi-Fi or 802.11) capability. Some establishments charge a fee for the use of their hot spots; others permit use free of charge. People who own laptops equipped with those Wi-Fi connec- tions can visit any of the hundreds of thousands (or perhaps millions) of Wi-Fi–equipped establishments and access the Internet to retrieve e-mail, visit Web sites, or whatever they do05_574183 ch01.qxd 7/23/04 10:05 AM Page 19 Chapter 1: Understanding Virus Risks 19 on the Internet. At a coffeehouse, for instance, you would pur- chase your tall double-shot vanilla low-fat latte and then sit down at one of the tables, turn on your laptop, and catch up on e-mail while quaffing your favorite coffee drink. But here’s the problem: These hot-spot connections have many of the same risks that are associated with always-on high-speed connections. Hackers and worms frequently scan the wireless networks in these establishments, hoping to find new victims — like, f’rinstance, your computer. Computers lacking adequate antivirus protection fall victim to the worm and become one of those zombie computers, awaiting the commands from their fiendish master. Downloading and file sharing If you or someone with access to your computer is doing a lot of file and program downloading and file sharing with others, chances are that sooner or later one of the files you download will be infected with a virus. Because many viruses travel from computer to computer by hiding inside of software program files, it makes sense that the more program files you bring into your system, the more likely it will be that one of them will have a virus. Also, program files that have been copied from other computers (rather than coming directly from the manufacturer) have a much greater chance of being infected with a virus. Instant messaging If you are an Instant Messaging (IM) user, you are increasing your chances of catching a virus (or, of course a worm, Trojan, or other ill fate). As the popularity of IM rises, so too does this get the attention of virus writers looking for new ways to get viruses from one computer to another. Already, there have been a number of worms that have propagated themselves using IM. Every day, minute by minute, you can be sure that there will have been more such incidents. Add-on programs If you are the type who can’t resist an online or computer store bargain, sooner or later something you pick up will have a little extra feature. While it doesn’t happen often, viruses have been known to sneak onto the gold (or final) version of a software manufacturer’s CD-ROM or online download area.05_574183 ch01.qxd 7/23/04 10:05 AM Page 20 Part I: Evaluating Your Virus Situation 20 How many viruses are there? Tens of thousands of viruses, worms, In the first half of 2003 alone, 3,855 new and Trojan horses have been devel- viruses were introduced. That is over oped and released onto the Internet 21 new viruses each and every day. over the past two decades. On the Nearly all new viruses are targeted day that I am writing this section, my at Microsoft products, including own PC’s antivirus program shows Windows, Outlook, and Office. over 66,000 known viruses in its list. And remember — virus writers like to get their viruses to propagate in large numbers. That means, some spend consid- erable time trying to get their wares into programs that will be mass-marketed or mass-distributed. Sharing your e-mail address with too many other people and organizations Persons who have a habit of signing up for things on the Internet are far more likely to end up on one or more spam- mers’ lists. Or if you are the type of person whose e-mail address is “in circulation” — meaning your e-mail address appears online in Web sites, chat rooms, mailing lists, news- groups, and so forth — then the chances improve that your e-mail address will be picked up and wind up in the hands of one or more mass marketers. As soon as this happens, one or more of the spammers who like to send large volumes (we’re talking millions) of virus-laden e-mail messages will take advantage of the target you’ve given them. This is not unlike giving out your phone number to lots of dif- ferent people and organizations, only to discover that you are beginning to receive far more unwanted phone calls than before. So it is with e-mail. It’s the fastest possible way to infest your once-pristine inbox with more unwanted mail than legitimate mail. In my case, about three-fourths of all the e-mail I receive is spam. My e-mail address appears in my online column in05_574183 ch01.qxd 7/23/04 10:05 AM Page 21 Chapter 1: Understanding Virus Risks 21 ComputerWorld. Of course, the address I use there is different from any I use anywhere else — and it isn’t hard to see why: Soon after I started writing my column, I began to receive additional spam, much of it sent to that unique address. This occurs because some spammers have spider programs that run all over the Web in search of e-mail addresses to harvest from Web sites. Deciding How Much Security Is Enough Without getting too scientific about it, the best way to think about “how much security is enough” is to compare the value of the possession you are trying to protect against the level of effort you’re willing to expend to protect it. Let me illustrate with a simple example. Would you protect a 1,000 automobile with a 2,000 alarm system? Not likely, because it isn’t proportional. Like shoes and bathing suits, one size does not fit all people and all needs. And so it is with computers. Depending on what you do with your computer, you will need to spend a particular level of effort in order to protect the information on your com- puter and the ability to continue performing whatever activities you use it for. For example, a casual user sends and receives e-mail and surfs the Internet. But someone else uses their computer to make their living: Perhaps they use their computer to build Web sites, do financial accounting for small businesses, or write For Dummies books. The latter user has a lot more to lose if something goes wrong with his or her computer, than does the casual user, who is merely inconvenienced. Take a look at three somewhat arbitrary levels of security in Table 1-1. Each one also represents a level of value, and I include examples of how often particular security activities should take place.05_574183 ch01.qxd 7/23/04 10:05 AM Page 22 Part I: Evaluating Your Virus Situation 22 Table 1-1 Levels of Security Typical Low Medium High Uses Casual e-mail, Family or business Small business computer correspondence, accounting, games, Web- online bill payment writer of For surfing Dummies books Virus Monthly Weekly Daily scans Virus Weekly Daily Hourly updates Risk High Medium Low tolerance Backups Infrequent Weekly Daily You can see in these examples that the higher-value systems deserve more elaborate protection. If you think about it, a high-value system is helping its owner to derive income or some other economic value, or pursue some other form of value that the user feels personally invested in. Given the risks associated with online computing, it makes sense to protect systems associated with economic (or other) value more than systems that were little more than hobbyist-level systems.06_574183 ch02.qxd 7/23/04 10:05 AM Page 23 Chapter 2 Does My Computer Have a Virus? In This Chapter  Looking at common virus symptoms  Finding and fixing a virus  Developing good habits  Finding out more about viruses oes your computer have a virus? Or are you just afraid Dthat your computer has a virus? Either way, you’ve come to the right place. If your computer has started to act funny — if it just doesn’t feel right — then it’s possible (but not cer- tain) that your computer has a virus. This chapter gives you the information necessary to help you determine whether your computer has a virus, and then points you in the right direction to find out what to do next. Just remember this: Nobody deserves to get a computer virus. If you do have a virus, batten down the hatches and brace for a fight — viruses are a pain in the neck at best, and they can be much worse. Armed with this book, however, you’re in a much better position to come out victorious in a scrape with a virus (and to avoid being infected in the future).06_574183 ch02.qxd 7/23/04 10:05 AM Page 24 Part I: Evaluating Your Virus Situation 24 Looking at Common Virus Symptoms Stalking the wild computer virus starts with observation: There are a lot of ways that a computer can begin to act strangely for no apparent reason. These changes in behavior may be the result of a virus, but there are other possible explanations as well. This section describes some typical virus-induced symptoms, as well as some ways to determine whether a virus is respon- sible for your computer’s symptoms. Computer too slow The first thing to check when your computer is slow is to make sure that your computer isn’t in a school zone. Seriously, a slowing in your computer can be the result of a number of circumstances — and a virus is definitely among them. The following list provides some considerations for making an educated guess as to why your computer is slowing down:  Have you made any changes to your computer lately? For instance, have you upgraded to Windows 2000 or Windows XP? These newer operating systems require a lot more memory than their predecessors.  Have you upgraded a program? Like Windows 2000 and Windows XP, newer versions of many other programs like Microsoft Office and Microsoft Works require a lot more memory than earlier versions.  Have you or a loved one downloaded a lot of “nature” pictures or other information? Pictures and music take up space. If your hard drive is almost full, your computer will definitely run slower. If you’re sure you haven’t made any changes, then you may have a virus. You’ll have to check your computer’s behavior and run a number of simple tests before you can be sure.06_574183 ch02.qxd 7/23/04 10:05 AM Page 25 Chapter 2: Does My Computer Have a Virus? 25 Unexplained activity Does your hard-drive or network-activity light flicker for no apparent reason? While there may be a legitimate reason for it, this could also be a sign that a virus or a hacker’s back-door program (a devious little program that allows secret access without your permission) is running on your computer. You might be donating some of your computer resources to a hacker and be largely unaware of it. Here are some examples of what could be going on if a hacker has gotten control of your computer:  The hacker could be using your computer to send thou- sands, even millions, of those annoying spam messages to people all over the Internet.  The hacker could be using your computer to launch attacks on corporate computing networks. In a DDoS (distributed denial of service) attack, for example, a hacker instructs thousands of “zombie” computers (like yours, perhaps) to send lots of messages to a particular corporate Web site, glutting its communications and knocking it off the Internet.  The hacker could be using your computer to scan other networks, hunting for vulnerable ports (communication channels for particular computer processes) that can mean more potential-victim computers.  The hacker may have installed spyware that reports back to the bad guys without the victim’s (your) knowl- edge. One example is a key logger — a small program that records every key press and mouse movement in an attempt to learn your bank-account numbers, credit-card numbers, and other sensitive information that you proba- bly don’t want strangers to know about. (For more about this insidious stuff, see “Blocking spyware,” later in this chapter.) Crashes or hangs Does your computer crash often? Does it just stop respond- ing? Do you often get the Blue Screen of Death™? Again, there are many possible explanations. No cop-out, just reality. (Hey, if I had a crystal ball, I’d quit writing, buy office space on Bourbon Street in New Orleans, and make my fortune, right?)06_574183 ch02.qxd 7/23/04 10:05 AM Page 26 Part I: Evaluating Your Virus Situation 26 Crashing, hanging, and blue screens may be virus-induced, but they’re probably not. These maladies are more likely the result of new software, new drivers, or even a hardware com- ponent that’s beginning to fail. Check out those possibilities first. Will not boot Boot used to be a noun — the leather thing you put on your foot to protect it from rough terrain. These days boot is a verb just as often; it’s the process that your computer performs to start itself when you turn it on or press Ctrl+Alt+Del (the “three-finger salute”). You guessed it — just because your computer won’t boot, it doesn’t necessarily mean that your computer has a virus. Maybe yes, maybe no. There are several other likely explana- tions — for example, a corrupted master boot record (the part of the hard drive that your computer uses to start up), or damage to an important file that your computer uses to start up. If either of these was the case, you’d probably have to rebuild your computer’s operating system and file system from scratch — not fun, even for the experts — and recover- ing any lost data could get dicey in a hurry. But you know, if you’re running Windows and have to reinstall your com- puter’s operating system, here are a couple of basic improve- ments to consider:  What better time to upgrade to Windows 2000 or Windows XP (unless you’re already running one of those)?  What better excuse to curl up with a good book — say, whichever Windows For Dummies book covers your newly installed version? This could be the perfect oppor- tunity to read up on Windows while you’re waiting for the install to finish. Strange computer behavior Okay, computers sometimes behave inscrutably, but their behavior should be predictable. Same deal for viruses — which means they can’t completely conceal their activities.06_574183 ch02.qxd 7/23/04 10:05 AM Page 27 Chapter 2: Does My Computer Have a Virus? 27 You can look for the devil in the details. Perhaps the signs are obvious (the colors go all weird, the computer puts words on-screen by itself, or it makes strange noises) or relatively subtle (your screen borders pinch inward for an instant just before you send e-mail). Time to observe closely and take notes. For openers, consider some “obvious” symptoms:  Files are not where you left them, and can’t be found on your computer. If your computer has become a Bermuda Triangle that is eating your files, even some of your soft- ware, you might have a virus.  You can find the file, but its size or date stamp is suspi- ciously different. Viruses that infect program files may make the files bigger or smaller than they should be, or change their date stamps. Date stamps don’t ordinarily change on program files — ever — unless an official soft- ware patch changes them. Uh-oh.  On-screen text starts to change by itself. In the old days of the DOS command prompt, one virus made the letters in on-screen text seem to move around “by themselves.” Sometimes they changed colors, or started consuming each other like Pac-Man. Bad sign. But you knew that.  An out-of-context message appears on-screen. Some viruses announce their presence by taunting the user. If you are greeted with a message such as Your computer is now Stoned, you probably have a virus. Consider whether the message is out of context — for example, does it look like someone’s trying to cap a practical joke with a punch line? Not funny at all. These are just a few examples of the weird things a virus can do to your computer. Those virus writers are pretty creative (in an ugly sort of way). Too many pop-up windows While I can’t prove it, I’d suspect that in some cases, Web sites that flood you with pop-up windows could also be attempting to download some malicious program(s) into your computer. Web sites that pump pop-ups into people’s computers are notorious for attempting to change the configuration of your Web browser and other parts of your computer — by remote control, without your knowledge or permission.06_574183 ch02.qxd 7/23/04 10:05 AM Page 28 Part I: Evaluating Your Virus Situation 28 Finding and Fixing a Virus There are some tools and procedures that can tell with 99.44 percent accuracy whether your computer has a virus. Here are the actions to take:  Find out whether your computer has antivirus software: Use Chapter 3 to help you find that out. If the steps in Chapter 3 lead you to believe that your computer does not have antivirus software, use Chapter 4 to help you obtain and install some.  Find out whether your antivirus software is up to date: If you already have antivirus software installed on your computer, Chapter 9 can help you figure out whether it’s up to date and working properly.  Scan your computer for viruses: When you know that your computer has antivirus software — and that it’s up to date — you can use it to scan your computer for viruses. Chapter 6 describes what to expect from this scan. If you have an Internet connection, you might think that you can take a shortcut and try one of those online virus- scanning tools — but don’t do that at this point The risks of connecting to the Internet without antivirus software and a firewall are greater than the benefit you’d get from knowing whether you have a virus — and you could end up with a virus if you use the ’Net unprotected. (It’s like drinking unboiled water from a polluted river — think Montezuma’s Revenge here.) For some really good reasons not to use an online scan- ning tool as a first resort, go to Chapters 6 through 10, where I explain local scanning, online scanning, and fire- walls. (Chapter 10 goes into detail about firewalls.) Suffice to say: Make sure you’re protected before you venture out.  Remove the virus: If your virus-scanning tool finds a virus on your computer, Chapter 7 explains how to get rid of the ugly thing. There are two basic outcomes: • Automatic removal: Chances are your virus- scanning tool will be able to fix your computer by removing the virus. Most of the time this is

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