Setting Up Secure Systems

1
Setting Up Secure Systems
2
Assessing security

• A well secured system requires a number of pieces
  of information
• What am I defending? Assets
• From who am I defending? Threats
• How will I know that a security breach has
  happened? Control
• What will I do when above occurs? Recovery

3
Assessing threats

• There are a number of ways of assessing threats
• Threat trees used in the States (very
  confidential documents!)
• CRAMM used in the UK
• The simplest can often be overlooked
• Theft is the biggest single cause of loss in the
  computer industry

4
OS threats - File Systems

• Access control for users
• Default permissions
• Group access rights
• Temporary files
• Secures files
• Password accounting data
• The kernel
• Privileged files/programs setuid on unix
• Devices files
• Spool queues

5
OS programs

• Dangerous commands
• Debuggers
• Admin commands
• Password commands
• Public domain software
• Bugs
• Accounting
• Monitoring
• Clock drift!
• Restricted accounts
• Rebooting
• Physical security

6
OS Users

• Passwords
• Accounts without
• Guest accounts
• Changing
• Sensible passwords
• Phantom accounts
• Groups
• Privileged accounts
• Special users