To make matters worse, network intrusion programs that automatically scan networks and query corporate DNS servers looking for holes are becoming increasingly available to hackers, who use these programs to test a system's locks the way a traditional burglar might jiggle a doorknob. Thankfully, all it takes is a bit of housekeeping to reduce your chances of becoming a victim. First, if yours is one of the many companies that runs outdated DNS software, an upgrade is definitely in order. Install the latest version of your DNS software immediately. Although services and file sharing capabilities are available on both Windows and Unix, Windows computers receive the brunt of file sharing attacks from Trojan horses and share compromises.
Many network administrators use share services to make data access more convenient.
But hackers will often compromise healthy machines by installing backdoor programs that register themselves as share services when users start their systems. To prevent unauthorized access through your network services, identify and remove all services that are not absolutely necessary. The same rule applies to new services, especially those that begin automatically at system startup. Nothing extraneous should ever be put into use. File shares present another potential vulnerability to your network because, when improperly configured, they can expose critical system files or even give full file system access to any party that is able to connect to your network.