A computer virus is a type of malware that, when executed, replicates by inserting copies of itself (possibly modified) into other computer programs, data files, or the boot sector of the hard drive; when this replication succeeds, the affected areas are then said to be "infected". Viruses often perform some type of harmful activity on infected hosts, such as stealing hard disk space or CPU time, accessing private information, corrupting data, displaying political or humorous messages on the user's screen, spamming their contacts, or logging their keystrokes.
Types of viruses that user should know!
• Boot Sector Virus: A Boot Sector Virus infects the first sector of the hard drive, where the Master Boot Record (MBR) is stored. The Master Boot Record (MBR) stores the disk's primary partition table and to store bootstrapping instructions which are executed after the computer's BIOS passes execution to machine code. If a computer is infected with Boot Sector Virus, when the computer is turned on, the virus launches immediately and is loaded into memory, enabling it to control the computer.
• File Deleting Viruses: A File Deleting Virus is designed to delete critical files which are the part of Operating System or data files.
• Mass Mailer Viruses: Mass Mailer Viruses search e-mail programs like MS outlook for e-mail addresses which are stored in the address book and replicate by e-mailing themselves to the addresses stored in the address book of the e-mail program.
• Macro viruses: Macro viruses are written by using the Macro programming languages like VBA, which is a feature of MS office package. A macro is a way to automate and simplify a task that you perform repeatedly in MS office suit (MS Excel, MS word etc). These macros are usually stored as part of the document or spreadsheet and can travel to other systems when these files are transferred to another computers.
• Polymorphic Viruses: Polymorphic viruses change their form in order to avoid detection and disinfection by anti-virus applications. After the work, these types of viruses try to hide from the anti-virus application by encrypting parts of the virus itself. This is known as mutation.
• Armored Viruses: Armored Viruses are type of viruses that are designed and written to make itself difficult to detect or analyze. An Armored Virus may also have the ability to protect itself from antivirus programs, making it more difficult to disinfect.
• Stealth viruses: Stealth viruses have the capability to hide from operating system or anti-virus software by making changes to file sizes or directory structure. Stealth viruses are anti-heuristic nature which helps them to hide from heuristic detection.
• Retrovirus: Retrovirus is another type virus which tries to attack and disable the anti-virus application running on the computer. A retrovirus can be considered anti-antivirus. Some Retroviruses attack the anti-virus application and stop it from running or some other destroys the virus definition database.
• Multiple Characteristic viruses: Multiple Characteristic viruses has different characteristics of viruses and have different capabilities.
How to prevent them!
1. Be sure do a full back up of your system on a regular basis. The best way to clean up an infected file is to replace it with an original non-infected file. Not to mention the grief a current back up will save if a virus takes your system completely down. It's also a good idea to keep more than one set of backup in case the current one is infected before the virus is detected.
2. Always use an anti-virus software program, one with both an on-demand and an on-access scanner. You'll want to look for one that has a fairly complete database of viruses and that is updatable. New viruses are produced daily, so it's important to have software that can detect the latest threat.
Be sure to read the manual and follow the directions of the software program to ensure it's protecting you properly. Also, consider buying and using two different brands to be doubly protected. See our review of anti-virus programs.
3. Update the virus database in your anti-virus program regularly (each month or by the direction of the manufacturer).
4. On a PC, change the CMOS setting of your boot up process from booting first on the A drive (floppy) and then on the C drive (hard drive) to just booting on the C drive. This will not only speed up your boot up process but also completely eliminate the risk of infecting your hard drive with an infected floppy disk.
If you should need to boot from a floppy you can easily change the settings back and reboot from the A drive. Please note: an infected non-bootable floppy disk can just as easily infect your hard drive as would an infected bootable one.
5. Don't allow your web browser to automatically run programs, such as MS Word or other programs through its e-mail program. Configure your browser to launch WordPad or Notepad instead. One of the biggest and growing threats is the macro virus, which is spread through data processing and spread sheet programs
6. Configure your web browsers to disable ActiveX, Java, and Javascript. You'll lose some of the fun the Web's been known for, but you'll save your computer from contracting a virus and speed up your connection.
7. Know that the only way a virus spreads is either by launching an infected file or by booting an infected disk. You can not get a virus by simply being online or by reading e-mail. You have to download and launch an infected file before it will spread. Therefore, do not launch any unsolicited executable files sent via e-mail.
8. Using an updated anti-virus program, scan all new software for viruses before installing them on your hard drive. Even shrink-wrapped software from major publishers has been known to contain viruses.
9. Be aware of hoaxes. To increase mass hysteria, there have been many stories conjured up and spread by un knowledgeable users. For a list of known hoaxes check out the following site:
• File Deleting Viruses: A File Deleting Virus is designed to delete critical files which are the part of Operating System or data files.
• Mass Mailer Viruses: Mass Mailer Viruses search e-mail programs like MS outlook for e-mail addresses which are stored in the address book and replicate by e-mailing themselves to the addresses stored in the address book of the e-mail program.
• Macro viruses: Macro viruses are written by using the Macro programming languages like VBA, which is a feature of MS office package. A macro is a way to automate and simplify a task that you perform repeatedly in MS office suit (MS Excel, MS word etc). These macros are usually stored as part of the document or spreadsheet and can travel to other systems when these files are transferred to another computers.
• Polymorphic Viruses: Polymorphic viruses change their form in order to avoid detection and disinfection by anti-virus applications. After the work, these types of viruses try to hide from the anti-virus application by encrypting parts of the virus itself. This is known as mutation.
• Armored Viruses: Armored Viruses are type of viruses that are designed and written to make itself difficult to detect or analyze. An Armored Virus may also have the ability to protect itself from antivirus programs, making it more difficult to disinfect.
• Stealth viruses: Stealth viruses have the capability to hide from operating system or anti-virus software by making changes to file sizes or directory structure. Stealth viruses are anti-heuristic nature which helps them to hide from heuristic detection.
• Retrovirus: Retrovirus is another type virus which tries to attack and disable the anti-virus application running on the computer. A retrovirus can be considered anti-antivirus. Some Retroviruses attack the anti-virus application and stop it from running or some other destroys the virus definition database.
• Multiple Characteristic viruses: Multiple Characteristic viruses has different characteristics of viruses and have different capabilities.
1. Be sure do a full back up of your system on a regular basis. The best way to clean up an infected file is to replace it with an original non-infected file. Not to mention the grief a current back up will save if a virus takes your system completely down. It's also a good idea to keep more than one set of backup in case the current one is infected before the virus is detected.
2. Always use an anti-virus software program, one with both an on-demand and an on-access scanner. You'll want to look for one that has a fairly complete database of viruses and that is updatable. New viruses are produced daily, so it's important to have software that can detect the latest threat.
Be sure to read the manual and follow the directions of the software program to ensure it's protecting you properly. Also, consider buying and using two different brands to be doubly protected. See our review of anti-virus programs.
3. Update the virus database in your anti-virus program regularly (each month or by the direction of the manufacturer).
4. On a PC, change the CMOS setting of your boot up process from booting first on the A drive (floppy) and then on the C drive (hard drive) to just booting on the C drive. This will not only speed up your boot up process but also completely eliminate the risk of infecting your hard drive with an infected floppy disk.
If you should need to boot from a floppy you can easily change the settings back and reboot from the A drive. Please note: an infected non-bootable floppy disk can just as easily infect your hard drive as would an infected bootable one.
5. Don't allow your web browser to automatically run programs, such as MS Word or other programs through its e-mail program. Configure your browser to launch WordPad or Notepad instead. One of the biggest and growing threats is the macro virus, which is spread through data processing and spread sheet programs
6. Configure your web browsers to disable ActiveX, Java, and Javascript. You'll lose some of the fun the Web's been known for, but you'll save your computer from contracting a virus and speed up your connection.
7. Know that the only way a virus spreads is either by launching an infected file or by booting an infected disk. You can not get a virus by simply being online or by reading e-mail. You have to download and launch an infected file before it will spread. Therefore, do not launch any unsolicited executable files sent via e-mail.
8. Using an updated anti-virus program, scan all new software for viruses before installing them on your hard drive. Even shrink-wrapped software from major publishers has been known to contain viruses.
9. Be aware of hoaxes. To increase mass hysteria, there have been many stories conjured up and spread by un knowledgeable users. For a list of known hoaxes check out the following site:
http://www.symantec.com/business/security_response/threatexplorer/risks/hoaxes.jsp
