All the time reports are published about famous and not-so-famous organizations which have had their networks and computers compromized by crackers. These reports  are probably only a small percentage of the real problem, since several organizations are reluctant to publish that they have been compromized.

There are several techniques and programs to use to secure your network from exploits from the outside.

Among other it is important to observe the following rules:

• Keep yourself informed about security weaknesses in your operating systems, applications and computer environment. There are several security mailing lists available which offer useful hints to secure your systems.
• Always install the latest patches which close security holes in your enviroment. Both UNIX vendors and Microsoft release patches often.
• Check that you do not have users with weaker security than the rest of the environment. As you know a chain is not stronger that its weakest link.
• Disable ports not in use.
• Examine the computers' logs and look for any unusual activity.
• A network environment is never secured once and for all. This is a continous process which needs person(s) responsible.

This week's security information will especially draw your attention to two excellent papers which describe how crackers work and think. Both papers are focused on UNIX based systems. The general approach however, should be useful whatever systems you use.

• Techniques Adopted By 'System Crackers' When Attempting To Break Into Corporate or Sensitive Private Networks (from Network Security Solutions)
• Improving the Security of Your Site by Breaking Into it ( Dan Farmer and Wietse Venema)

Per Olav Førland