This is not any multiple lists of reasons for you to have a firewall & software patched, but just only one very good reason for you to have them. There are two recent study posted on SecurityNewsDaily on this subject and had concluded that 99% of Malware attack developed on top of Windows can be prevented simply by having a firewall and up-to-date software patches.
Independent security researcher Craig S. Wright, had done some studies on 640 Windows XP machines where in his studies, he focused on infecting those machines with Malware on the condition of having a firewall and not having a firewall together with up-to-date patches on its software.
Of all the 640 machines that does not have a firewall installed, one of them got infected in less than 5 seconds. While on the maximum survival time, those computers does not last any longer than 108 hours, which is around 5 days. So read carefully, if you are using a Windows XP machine without firewall installed and somehow has Malware attacking you, your computer might not last any longer than 5 days.
It is hard not to conclude that the Windows Firewall makes a statistically significant difference to the security of the system.
– Craig S. Wright
Another security study done by a Peter Kruse of CSIS on “exploit kits”, some hacking tool developed by online criminal to hack into any internet users has concluded that as much as 99.8% malware infections are caused by these commercial tool on un-patched system.
As a result, those malware might not stand a chance at all against a fully patched system specifically on these five items which are Microsoft Internet Explorer, Microsoft Help and Support, Adobe Flash Player, Adobe Acrobat/Reader and Java Runtime Engine.
Although at the end, Wright quoted that “Even the best-configured system fails in time”, that does not mean we should not take the effort to protect ourselves. The very basic needs now for you to stay secure is to ensure your firewall is switched on and run an update on your software especially the five items mentioned.