Computer Virus and its effect on computer system
1.0
Introduction
1.1
Background
A computer virus is a special kind of computer program which spreads across disks and networks by making copies of it self , usually surreptitiously. Can produce undesired side-effects in computer in which it is active.
A computer virus is a special kind of computer program which spreads across disks and networks by making copies of it self , usually surreptitiously. Can produce undesired side-effects in computer in which it is active.
1.2
Aims
The purpose of this report is to aware people, how they can protect there data and systems from any computer virus by using computer tools and anti-viruses like Avast, 360 Total Security etc.
The purpose of this report is to aware people, how they can protect there data and systems from any computer virus by using computer tools and anti-viruses like Avast, 360 Total Security etc.
1.3 Scope
The reports evaluates these areas such as protection from computer virus and positive effect of computer viruses . How computer virus spreads from one system to an other system and how it effect computer system.
The reports evaluates these areas such as protection from computer virus and positive effect of computer viruses . How computer virus spreads from one system to an other system and how it effect computer system.
1.4 Infection
In order to infect a computer, a virus has to have the chance to execute its code. Viruses usually ensure that this happens by behaving like a parasite, i.e. by modifying another item so that the virus code is executed when the legitimate item is run or opened. Good vehicles for viruses include the parts of a disk which contain code executed whenever that disk is booted, and documents which contain macros executed whenever that document is opened with the relevant application. As long as the virus is active on the computer, it can copy itself to other files or disks that are accessed.
In order to infect a computer, a virus has to have the chance to execute its code. Viruses usually ensure that this happens by behaving like a parasite, i.e. by modifying another item so that the virus code is executed when the legitimate item is run or opened. Good vehicles for viruses include the parts of a disk which contain code executed whenever that disk is booted, and documents which contain macros executed whenever that document is opened with the relevant application. As long as the virus is active on the computer, it can copy itself to other files or disks that are accessed.
1.5
Viruses escape detection
The successful spread of a virus depends on how long it can replicate unnoticed, before its presence is made known by the activation of side-effects. Viruses use two main methods of disguise Encrypting (scrambling) their code to avoid reorganization. Preventing application from seeing the virus in memory, by interrupt interception or (in case of macro viruses) by disabling the options to view macros.
The successful spread of a virus depends on how long it can replicate unnoticed, before its presence is made known by the activation of side-effects. Viruses use two main methods of disguise Encrypting (scrambling) their code to avoid reorganization. Preventing application from seeing the virus in memory, by interrupt interception or (in case of macro viruses) by disabling the options to view macros.
2.0
Historical Background
2.1 Computer Virus
Computers and computer users are under assault by hackers like never before, but computer viruses are almost as old as electronic computers themselves. Most people use the term “computer virus” to refer to all malicious software, which we call malware. Computer Viruses are actually just one type of malware, a self-replicating programs designed to spread itself from computer to computer. A virus is, in fact, the earliest known malware invented. Traditional computer viruses were first widely seen in the late 1980s, and came about because of several factors. The first factor was the spread of personal computer (PCs) Prior to the 1980s home computers were nearly non-existent. Real computers were rare, and were locked away for use by "experts." During the '80s, real computers started to spread to businesses and homes because of the popularity of the IBM PC (released in 1982) and the Apple Macintosh (released in 1984). By the late 1980s, PCs were in businesses, homes and college campuses. The second factor was the use of computer bulletin boards. People could dial up a bulletin board with a modem and download programs of all types. Games were extremely popular, and so were simple word processors, spreadsheets and other productivity software. Bulletin boards led to the precursor of the virus known as the Trojan horse. A Trojan horse masquerades as a program with a cool-sounding name and description, enticing you to download it. When you run the program, however, it does something un cool, like erasing your hard drive. You think you're getting a neat game, but instead, you get a wiped-out system. Trojans horses only hit a small number of people because they're quickly discovered, and word of the danger spreads among users. The third factor that led to the creation of viruses was the floppy disk. In the 1980s, programs were small, and you could fit the entire operating system a few programs and some documents onto a floppy disk or two. Many computers did not have hard disks, so when you turned on your machine it would load the operating system and everything else from the floppy disk. Virus authors took advantage of this to create the first self-replicating programs. Early viruses were pieces of code embedded in a larger, legitimate program, such as a game or word processor. When the user downloads and runs the legitimate program, he virus loads itself into memory and looks around to see if it can find any other programs on the disk. If it find one, it modifies the program to add the virus’s code into that program. Then the virus launches the "real program." The user really has no way to know that the virus ever ran. Unfortunately, the virus has now reproduced itself, so two programs are infected. The next time the user launches either of those programs, they infect other programs, and the cycle continues. If one of the infected programs is given to another person on a floppy disk, or if it is uploaded so other people can download it, then other programs get infected. This is how the virus spreads -- similar to the infection phase of a biological virus. But viruses wouldn't be so violently despised if all they did was replicate them selves. Most viruses also have a destructive attack phase where they do real damage. Some sort of trigger will activate the attack phase, and the virus will then do something -- anything from displaying a silly message on the screen to erasing all of your data. The trigger might be a specific date, a number of times the virus has been replicated or something similar.
Computers and computer users are under assault by hackers like never before, but computer viruses are almost as old as electronic computers themselves. Most people use the term “computer virus” to refer to all malicious software, which we call malware. Computer Viruses are actually just one type of malware, a self-replicating programs designed to spread itself from computer to computer. A virus is, in fact, the earliest known malware invented. Traditional computer viruses were first widely seen in the late 1980s, and came about because of several factors. The first factor was the spread of personal computer (PCs) Prior to the 1980s home computers were nearly non-existent. Real computers were rare, and were locked away for use by "experts." During the '80s, real computers started to spread to businesses and homes because of the popularity of the IBM PC (released in 1982) and the Apple Macintosh (released in 1984). By the late 1980s, PCs were in businesses, homes and college campuses. The second factor was the use of computer bulletin boards. People could dial up a bulletin board with a modem and download programs of all types. Games were extremely popular, and so were simple word processors, spreadsheets and other productivity software. Bulletin boards led to the precursor of the virus known as the Trojan horse. A Trojan horse masquerades as a program with a cool-sounding name and description, enticing you to download it. When you run the program, however, it does something un cool, like erasing your hard drive. You think you're getting a neat game, but instead, you get a wiped-out system. Trojans horses only hit a small number of people because they're quickly discovered, and word of the danger spreads among users. The third factor that led to the creation of viruses was the floppy disk. In the 1980s, programs were small, and you could fit the entire operating system a few programs and some documents onto a floppy disk or two. Many computers did not have hard disks, so when you turned on your machine it would load the operating system and everything else from the floppy disk. Virus authors took advantage of this to create the first self-replicating programs. Early viruses were pieces of code embedded in a larger, legitimate program, such as a game or word processor. When the user downloads and runs the legitimate program, he virus loads itself into memory and looks around to see if it can find any other programs on the disk. If it find one, it modifies the program to add the virus’s code into that program. Then the virus launches the "real program." The user really has no way to know that the virus ever ran. Unfortunately, the virus has now reproduced itself, so two programs are infected. The next time the user launches either of those programs, they infect other programs, and the cycle continues. If one of the infected programs is given to another person on a floppy disk, or if it is uploaded so other people can download it, then other programs get infected. This is how the virus spreads -- similar to the infection phase of a biological virus. But viruses wouldn't be so violently despised if all they did was replicate them selves. Most viruses also have a destructive attack phase where they do real damage. Some sort of trigger will activate the attack phase, and the virus will then do something -- anything from displaying a silly message on the screen to erasing all of your data. The trigger might be a specific date, a number of times the virus has been replicated or something similar.
3.0
Effect on computer
3.1
Types
3.1.1 Memory Resident Virus
These viruses fix themselves in the computer memory and get activated whenever the OS runs and infects all the files that are then opened.
Hideout: This type of virus hides in the RAM and stays there even after the malicious code is executed. It gets control over the system memory and allocate memory blocks through which it runs its own code, and executes the code when any function is executed.
Target: It can corrupt files and programs that are opened, closed, copied, renamed, etc.Examples: Randex, CMJ, Meve, and MrKlunky
Protection: Install an antivirus program.
3.1.2 Direct Action Virus
The main purpose of this virus is to replicate and take action when it is executed. When a specific condition is met, the virus will go into action and infect files in the directory or folder that are specified in the AUTOEXEC.BAT file path. This batch file is always located in the root directory of the hard disk and carries out certain operations when the computer is booted. FindFirst/FindNext technique is used where the code selects a few files as its victims. It also infects the external devices like pen drives or hard disks by copying itself on them.
Hideout: The viruses keep changing their location into new files whenever the code is executed, but are generally found in the hard disk's root directory.
Target: It can corrupt files. Basically, it is a file-infector virus.
Examples: Vienna virus
Protection: Install an antivirus scanner. However, this type of virus has minimal effect on the computer's performance.
3.1.3 Overwrite Virus
A virus of this kind is characterized by the fact that it deletes the information contained in the files that it infects, rendering them partially or totally useless once they have been infected.
Hideout: The virus replaces the file content. However, it does not change the file size.
Examples: Way, Trj.Reboot, Trivial.88.D
Protection: The only way to clean a file infected by an overwrite virus is to delete the file completely, thus losing the original content.
However, it is very easy to detect this type of virus, as the original program becomes useless.
3.1.4 Boot Sector virus
This type of virus affects the boot sector of a hard disk. This is a crucial part of the disk, in which information of the disk itself is stored along with a program that makes it possible to boot (start) the computer from the disk. This type of virus is also called Master Boot Sector Virus or Master Boot Record Virus.
Hideout: It hides in the memory until DOS accesses the floppy disk, and whichever boot data is accessed, the virus infects it.
Examples: Polyboot.B, AntiEXE
Protection: The best way of avoiding boot sector viruses is to ensure that floppy disks are write-protected. Also, never start your computer with an unknown floppy disk in the disk drive.
4.1.5 Macro Virus
Macro viruses infect files that are created using certain applications or programs that contain macros, like .doc, .xls, .pps, .mdb, etc. These mini-programs make it possible to automate series of operations so that they are performed as a single action, thereby saving the user from having to carry them out one by one. These viruses automatically infect the file that contains macros, and also infects the templates and documents that the file contains. It is referred to as a type of e-mail virus.
Hideout: These hide in documents that are shared via e-mail or networks.
Examples: Relax, Melissa.A, Bablas, O97M/Y2K
Protection: The best protection technique is to avoid opening e-mails from unknown senders. Also, disabling macros can help to protect your useful data.
3.1.6 Directory Virus
Directory viruses (also called Cluster Virus/File System Virus) infect the directory of your computer by changing the path that indicates the location of a file. When you execute a program file with an extension .EXE or .COM that has been infected by a virus, you are unknowingly running the virus program, while the original file and program is previously moved by the virus. Once infected, it becomes impossible to locate the original files.
Hideout: It is usually located in only one location of the disk, but infects the entire program in the directory.
Examples: Dir-2 virus
Protection: All you can do is, reinstall all the files from the backup that are infected after formatting the disk
3.1.7 Polymorphic Virus
Polymorphic viruses encrypt or encode themselves in a different way (using different algorithms and encryption keys) every time they infect a system. This makes it impossible for antivirus software to find them using string or signature searches (because they are different in each encryption). The virus then goes on to create a large number of copies.
Examples: Elkern, Marburg, Satan Bug and Tuareg
Protection: Install a high-end antivirus as the normal ones are incapable of detecting this type of virus
3.1.8 Companion Virus
Companion viruses can be considered as a type of file infector virus, like resident or direct action types. They are known as companion viruses because once they get into the system they 'accompany' the other files that already exist. In other words, to carry out their infection routines, companion viruses can wait in memory until a program is run (resident virus), or act immediately by making copies of themselves (direct action virus).
Hideout: These generally use the same filename and create a different extension of it.
For example: If there is a file "Me.exe", the virus creates another file named "Me.com" and hides in the new file. When the system calls the filename "Me", the ".com" file gets executed (as ".com" has higher priority than ".exe"), thus infecting the system.
Examples: Stator, Asimov.1539 and Terrax.1069
Protection: Install an antivirus scanner and also download Firewall.
3.1.9 FAT Virus
The file allocation table (FAT) is the part of a disk used to store all the information about the location of files, available space, unusable space, etc.
Hideout: FAT virus attacks the FAT section and may damage crucial information. It can be especially dangerous as it prevents access to certain sections of the disk where important files are stored. Damage caused can result in loss of information from individual files or even entire directories.
Examples: Link Virus
Protection: Before the virus attacks all the files on the computer, locate all the files that are actually needed on the hard drive, and then delete the ones that are not needed. They may be files created by viruses.
3.1.10 Multipartite Virus
These viruses spread in multiple ways possible. It may vary in its action depending upon the operating system installed and the presence of certain files.
Hideout: In the initial phase, these viruses tend to hide in the memory as the resident viruses do; then they infect the hard disk.
Examples: Invader, Flip and Tequila
Protection: You need to clean the boot sector and also the disk to get rid of the virus, and then reload all the data in it. However, ensure that the data is clean.
3.1.11 Web Scripting Virus
Many web pages include complex codes in order to create an interesting and interactive content. This code is often exploited to bring about certain undesirable actions.
Hideout: The main sources of web scripting viruses are the web browsers or infected web pages.
Examples: JS.Fortnight is a virus that spreads through malicious e-mails.
Protection: Install the Microsoft tool application that is a default feature in Windows 2000, Windows 7 and Vista. Scan the computer with this application.
3.1.12 Worms
A worm is a program very similar to a virus; it has the ability to self-replicate and can lead to negative effects on your system. But they can be detected and eliminated by an antivirus software.
Hideout: These generally spread through e-mails and networks. They do not infect files or damage them, but they replicate so fast that the entire network may collapse.
Examples: PSWBugbear.B, Lovgate.F, Trile.C, Sobig.D, Mapson
Protection: Install an updated version of antivirus.
3.1.13 Trojans
Another unsavory breed of malicious code are Trojans or Trojan horses, which unlike viruses, do not reproduce by infecting other files, nor do they self-replicate like worms. In fact, it is a program which disguises itself as a useful program or application.
3.1.1 Memory Resident Virus
These viruses fix themselves in the computer memory and get activated whenever the OS runs and infects all the files that are then opened.
Hideout: This type of virus hides in the RAM and stays there even after the malicious code is executed. It gets control over the system memory and allocate memory blocks through which it runs its own code, and executes the code when any function is executed.
Target: It can corrupt files and programs that are opened, closed, copied, renamed, etc.Examples: Randex, CMJ, Meve, and MrKlunky
Protection: Install an antivirus program.
3.1.2 Direct Action Virus
The main purpose of this virus is to replicate and take action when it is executed. When a specific condition is met, the virus will go into action and infect files in the directory or folder that are specified in the AUTOEXEC.BAT file path. This batch file is always located in the root directory of the hard disk and carries out certain operations when the computer is booted. FindFirst/FindNext technique is used where the code selects a few files as its victims. It also infects the external devices like pen drives or hard disks by copying itself on them.
Hideout: The viruses keep changing their location into new files whenever the code is executed, but are generally found in the hard disk's root directory.
Target: It can corrupt files. Basically, it is a file-infector virus.
Examples: Vienna virus
Protection: Install an antivirus scanner. However, this type of virus has minimal effect on the computer's performance.
3.1.3 Overwrite Virus
A virus of this kind is characterized by the fact that it deletes the information contained in the files that it infects, rendering them partially or totally useless once they have been infected.
Hideout: The virus replaces the file content. However, it does not change the file size.
Examples: Way, Trj.Reboot, Trivial.88.D
Protection: The only way to clean a file infected by an overwrite virus is to delete the file completely, thus losing the original content.
However, it is very easy to detect this type of virus, as the original program becomes useless.
3.1.4 Boot Sector virus
This type of virus affects the boot sector of a hard disk. This is a crucial part of the disk, in which information of the disk itself is stored along with a program that makes it possible to boot (start) the computer from the disk. This type of virus is also called Master Boot Sector Virus or Master Boot Record Virus.
Hideout: It hides in the memory until DOS accesses the floppy disk, and whichever boot data is accessed, the virus infects it.
Examples: Polyboot.B, AntiEXE
Protection: The best way of avoiding boot sector viruses is to ensure that floppy disks are write-protected. Also, never start your computer with an unknown floppy disk in the disk drive.
4.1.5 Macro Virus
Macro viruses infect files that are created using certain applications or programs that contain macros, like .doc, .xls, .pps, .mdb, etc. These mini-programs make it possible to automate series of operations so that they are performed as a single action, thereby saving the user from having to carry them out one by one. These viruses automatically infect the file that contains macros, and also infects the templates and documents that the file contains. It is referred to as a type of e-mail virus.
Hideout: These hide in documents that are shared via e-mail or networks.
Examples: Relax, Melissa.A, Bablas, O97M/Y2K
Protection: The best protection technique is to avoid opening e-mails from unknown senders. Also, disabling macros can help to protect your useful data.
3.1.6 Directory Virus
Directory viruses (also called Cluster Virus/File System Virus) infect the directory of your computer by changing the path that indicates the location of a file. When you execute a program file with an extension .EXE or .COM that has been infected by a virus, you are unknowingly running the virus program, while the original file and program is previously moved by the virus. Once infected, it becomes impossible to locate the original files.
Hideout: It is usually located in only one location of the disk, but infects the entire program in the directory.
Examples: Dir-2 virus
Protection: All you can do is, reinstall all the files from the backup that are infected after formatting the disk
3.1.7 Polymorphic Virus
Polymorphic viruses encrypt or encode themselves in a different way (using different algorithms and encryption keys) every time they infect a system. This makes it impossible for antivirus software to find them using string or signature searches (because they are different in each encryption). The virus then goes on to create a large number of copies.
Examples: Elkern, Marburg, Satan Bug and Tuareg
Protection: Install a high-end antivirus as the normal ones are incapable of detecting this type of virus
3.1.8 Companion Virus
Companion viruses can be considered as a type of file infector virus, like resident or direct action types. They are known as companion viruses because once they get into the system they 'accompany' the other files that already exist. In other words, to carry out their infection routines, companion viruses can wait in memory until a program is run (resident virus), or act immediately by making copies of themselves (direct action virus).
Hideout: These generally use the same filename and create a different extension of it.
For example: If there is a file "Me.exe", the virus creates another file named "Me.com" and hides in the new file. When the system calls the filename "Me", the ".com" file gets executed (as ".com" has higher priority than ".exe"), thus infecting the system.
Examples: Stator, Asimov.1539 and Terrax.1069
Protection: Install an antivirus scanner and also download Firewall.
3.1.9 FAT Virus
The file allocation table (FAT) is the part of a disk used to store all the information about the location of files, available space, unusable space, etc.
Hideout: FAT virus attacks the FAT section and may damage crucial information. It can be especially dangerous as it prevents access to certain sections of the disk where important files are stored. Damage caused can result in loss of information from individual files or even entire directories.
Examples: Link Virus
Protection: Before the virus attacks all the files on the computer, locate all the files that are actually needed on the hard drive, and then delete the ones that are not needed. They may be files created by viruses.
3.1.10 Multipartite Virus
These viruses spread in multiple ways possible. It may vary in its action depending upon the operating system installed and the presence of certain files.
Hideout: In the initial phase, these viruses tend to hide in the memory as the resident viruses do; then they infect the hard disk.
Examples: Invader, Flip and Tequila
Protection: You need to clean the boot sector and also the disk to get rid of the virus, and then reload all the data in it. However, ensure that the data is clean.
3.1.11 Web Scripting Virus
Many web pages include complex codes in order to create an interesting and interactive content. This code is often exploited to bring about certain undesirable actions.
Hideout: The main sources of web scripting viruses are the web browsers or infected web pages.
Examples: JS.Fortnight is a virus that spreads through malicious e-mails.
Protection: Install the Microsoft tool application that is a default feature in Windows 2000, Windows 7 and Vista. Scan the computer with this application.
3.1.12 Worms
A worm is a program very similar to a virus; it has the ability to self-replicate and can lead to negative effects on your system. But they can be detected and eliminated by an antivirus software.
Hideout: These generally spread through e-mails and networks. They do not infect files or damage them, but they replicate so fast that the entire network may collapse.
Examples: PSWBugbear.B, Lovgate.F, Trile.C, Sobig.D, Mapson
Protection: Install an updated version of antivirus.
3.1.13 Trojans
Another unsavory breed of malicious code are Trojans or Trojan horses, which unlike viruses, do not reproduce by infecting other files, nor do they self-replicate like worms. In fact, it is a program which disguises itself as a useful program or application.
4.0
Conclusion
New viral environments are discovered each year. Over the last 20 years of PC viruses, there has been tremendous dark energy in place to develop computer viruses for almost every platform imaginable. All over the world, thousands of people created computer viruses. Because of this we are experiencing an ever-growing security problem with malicious code and, consequently, seeing the development of computer virus research as a new scientific field. There is absolutely no question whether computer viruses will stay with us and evolve to future platforms in the upcoming decades. Viruses are very destructive programs that can be devastating to companies and individuals. Upon completion of this report people should be able to have an understanding of the following: what viruses are, how they get into a computer, how viruses can be avoided, how you get rid of viruses, and the best type of software used to prevent viruses. Fred Cohen's initial research with computer viruses in 1984 concluded that the computer virus problem is ultimately an integrity problem. Over the last 20 years, the scope of integrity expanded dramatically from file integrity to the integrity of applications and operating system software. Modern computer viruses, such as W32/CodeRed and W32/Slammer, clearly indicate this new era: Computer viruses cannot be controlled by file-based integrity checking alone because they jump from system to system over the network, injecting themselves into new process address spaces in such a way that they are never stored on the disk.
New viral environments are discovered each year. Over the last 20 years of PC viruses, there has been tremendous dark energy in place to develop computer viruses for almost every platform imaginable. All over the world, thousands of people created computer viruses. Because of this we are experiencing an ever-growing security problem with malicious code and, consequently, seeing the development of computer virus research as a new scientific field. There is absolutely no question whether computer viruses will stay with us and evolve to future platforms in the upcoming decades. Viruses are very destructive programs that can be devastating to companies and individuals. Upon completion of this report people should be able to have an understanding of the following: what viruses are, how they get into a computer, how viruses can be avoided, how you get rid of viruses, and the best type of software used to prevent viruses. Fred Cohen's initial research with computer viruses in 1984 concluded that the computer virus problem is ultimately an integrity problem. Over the last 20 years, the scope of integrity expanded dramatically from file integrity to the integrity of applications and operating system software. Modern computer viruses, such as W32/CodeRed and W32/Slammer, clearly indicate this new era: Computer viruses cannot be controlled by file-based integrity checking alone because they jump from system to system over the network, injecting themselves into new process address spaces in such a way that they are never stored on the disk.
5.0
Recommendations
Install an antivirus program. Installing an antivirus program and keeping it up to date can help defend your computer against viruses. Antivirus programs scan for viruses trying to get into your email, operating system, or files. New viruses appear daily, so set your antivirus software to install updates automatically.
Don't open email attachments unless you're expecting them. Many viruses are attached to email messages and will spread as soon as you open the email attachment. It's best not to open any attachment unless it's something you're expecting.
Keep your computer updated. Microsoft releases security updates that can help protect your computer. Make sure that Windows receives these updates by turning on Windows automatic updating.
Use a firewall. Windows Firewall (or any other firewall) can help alert you to suspicious activity if a virus or worm attempts to connect to your computer. It can also block viruses, worms, and hackers from attempting to download potentially harmful programs to your computer.
Use your browser's privacy settings. Being aware of how websites might use your private information is important to help prevent fraud and identity theft. If you're using Internet Explorer, you can adjust your Privacy settings or restore the default settings whenever you want.
Use a pop-up blocker with your browser. Pop-up windows are small browser windows that appear on top of the website you're viewing. Although most are created by advertisers, they can also contain malicious or unsafe code. A pop-up blocker can prevent some or all of these windows from appearing. The Pop-up Blocker feature in Internet Explorer is turned on by default. To learn more about changing its settings or turning it on and off.
Install an antivirus program. Installing an antivirus program and keeping it up to date can help defend your computer against viruses. Antivirus programs scan for viruses trying to get into your email, operating system, or files. New viruses appear daily, so set your antivirus software to install updates automatically.
Don't open email attachments unless you're expecting them. Many viruses are attached to email messages and will spread as soon as you open the email attachment. It's best not to open any attachment unless it's something you're expecting.
Keep your computer updated. Microsoft releases security updates that can help protect your computer. Make sure that Windows receives these updates by turning on Windows automatic updating.
Use a firewall. Windows Firewall (or any other firewall) can help alert you to suspicious activity if a virus or worm attempts to connect to your computer. It can also block viruses, worms, and hackers from attempting to download potentially harmful programs to your computer.
Use your browser's privacy settings. Being aware of how websites might use your private information is important to help prevent fraud and identity theft. If you're using Internet Explorer, you can adjust your Privacy settings or restore the default settings whenever you want.
Use a pop-up blocker with your browser. Pop-up windows are small browser windows that appear on top of the website you're viewing. Although most are created by advertisers, they can also contain malicious or unsafe code. A pop-up blocker can prevent some or all of these windows from appearing. The Pop-up Blocker feature in Internet Explorer is turned on by default. To learn more about changing its settings or turning it on and off.
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