Security
Networked Computer Systems 1
Security
Levels of Threat
The level of system security required
depends upon the expertise of the
attacker.
1. Ordinary web user
2. Sophisticated user (CS students)
3. Professional Thief
4. Insider
5. Corporate
6. Government
Cost of Security
• Security has a cost in hardware,
software and user convenience.
• The cost of defeating a security
system must be greater than
the value of the data it protects.
Security Goals
The goals for protecting any system are to
assure that the following criteria are met:
1. Availability – services up and running.
2. Integrity Control– data is created/modified by
authorized parties only.
3. Secrecy/Confidentiality – access is restricted to
authorized parties.
4. Authentication – verifying identity
5. Non-repudiation – verification of action or data
Threats to System Security
Threats to network security typically come
in any of four forms:
1. Interception – sniffing, wiretapping, eavesdropping
2. Modification – unauthorized access/tampering
3. Fabrication – impersonation or fabrication of data
or objects to gain access to services/information.
4. Interruption – Denial of Service
Methods of Attack
• Eavesdropping
– Viewing data or passwords on the network.
– Easy to do on broadcast networks.
• Message Tampering
– Changing messages as they travel the
network.
• Masquerading
– Sending messages and programs with
invalid sender identification.
Docsity.com
