Other computer protection methods

Other computer protection methods

Beside antivirus software, virus infection prevention can be assisted by other means such as implementing a network firewall, or utilizing system virtualization^{[citation needed]}.

[edit] Antivirus Card

This method was used in the early 1990s by DOS users and involves the installation of an ISA interface card which takes over the DOS interrupt and monitors the WRITE operation.

[edit] Network Firewall

Network firewalls prevent unknown programs and Internet processes from accessing the system protected. However, they are not antivirus systems as such and thus make no attempt to identify or remove anything. They may protect against infection from outside the protected computer or LAN, and limit the activity of any malicious software which is present by blocking incoming or outgoing requests on certain TCP/IP ports. A firewall is designed to deal with broader system threats that come from network connections into the system and is not an alternative to a virus protection system.

[edit] System Virtualization

This method virtualizes the working system, which prevents the actual system from being altered by a virus as it stops any alteration attempts to the whole system under virtualization. Although this may in general be the case, infection may spread to the non-virtual system if the virus is so conceived that after infecting the virtual system, it will break (crack) the virtualization environment by using one of its exploits and then spread to the non-virtual environment.^{[citation needed]}

In general, without any antivirus software the virtual system can still be infected and suffer damage or malicious action, but as soon as the system is shut down and restarted, all the changes and damage previously done to the virtual system will be reset. This way, the system is protected and the virus is removed. However, any damages to unprotected or unvirtualized data will remain, as will the malicious effects it has caused such as data theft.^{[citation needed]}

Since not all virtualization software loads the virtual computer from a standard (unchangeable) boot image, in certain cases it works just as any real computer which has its own (virtual) hard disk, i.e. infection with a virus will have to be cured in order to disinfect the system, or the virtual system will have to be destroyed (deleted) in order to get rid of the damage. This is the case for VMware and VirtualPC, if there is set up a virtual computer with its own virtual hard disk. Virtualization software like Sandboxie may prevent infection from spreading to the main (non-virtual) system and then indeed the only damage made by the virus is data/identity theft, i.e. stealing the data which is made available by the non-virtual system to the virtual browsing/document processing environment. As mentioned before, if Sandboxie has exploits, a virus may use such exploits in order to infect the non-virtual environment.^{[citation needed]}