Winning a zero-day exploit means being prepared for unexpected intrusions into a computer network by having more protection than is afforded by an operating system. what hackers do is look for holes or bugs in an operating system or software that has the authority to access the internet. These bugs can often be exploited in such a way as to gain access to a system and to make it behave in a way different from normal.
Someone who figures out how to take advantage of a discovered hole and then uses it to attack a computer network before the hole is patched is making a zero day attack. This means that the company responsible for the software is unaware of the bug and has had zero days to do something about it. For the hacker, it means that they are using the leading edge of information.
It is hard for a company with sensitive files or a vulnerable network system to do much about it because they are not aware of the hole and neither is the company that provides security. The only real countermeasures are to have the experts on hand that know how to defend against a zero-day attack or else to use security measures that are tougher to crack into.
A company is less likely to be hacked if either a hacker does not know about the network or else they underestimate its value. It is hard to hide the nature of a company, but it is possible to avoid making enemies or to leak details of a computer network. What is not targeted is not vulnerable.
Being able to rapidly respond to an intrusion is another way of dealing with it. Someone who needs security very badly can always hire someone to study what is going on with the network all the time in order to make fast decisions to an apparent attack. Some companies have a whole team of IT experts for this purpose, although every network should have at least one in order to make initial decisions and the preliminary investigation.
Good security software helps to blow the whistle on intruders. One of the most secure network setups is to have a physical firewall device separate the network from the internet and then the network station from the local network. Since these firewalls have the ability to sniff traffic, they can detect anomalies long before human technicians who have the tendency to become complacent after a few years on the job.
